I had to give an important talk about my field. Then during the talk a professor asked a question, he wanted me to give an example in a different situation. I tried to remember and told him the equations I recalled (I didn’t work with that for quite some time now), but then I realized after the talk I made a small mistake in each. The formulas were slightly different, but the difference is important.

In any case, the issue is that the talk is recorded and will be on youtune. If not for that, people would most certainly forget this, but it is recorded. Is it super bad that I messed up that and didn’t remember it properly? Or is it acceptable? I’m a postdoc, and this was really the first more important talk I gave.

  • 15
    FWIW: I always appreciate people making mistakes, because it destroys the illusion that everyone knows anything at all times. It's human and normal to forget things or remember them slightly wrong and it doesn't set absurd standards to students. As mentioned in an answer, just put an Errata up and be done about it. Commented May 30 at 11:25
  • It's ok, nobody goes on youtune. Commented Jun 4 at 10:17

3 Answers 3


It should not be a big deal at all. Very, very few people watch math talks on YouTube. Also, you could easily edit the YouTube description (or ask for it to be edited, or leave a comment) explaining the minor modifications needed to make it correct at that time stamp. That kind of thing is very common, with all the talks people recorded during the pandemic, and all the inevitable mistakes that were made.

  • 23
    +1 for description and comment! Also, the comment containing the errata should be pinned so that it stays at the very top, just below the video.
    – SylvainD
    Commented May 30 at 7:16
  • 27
    I sort of disagree with "very, very few people watch math talks on YouTube". It's not wrong - very few people study maths at all - but of those that do, I would guess that the vast majority of them watch talks on YouTube sometimes. A maths talk generally gets a small audience, but it's likely to be made up of people whose opinions the OP cares about. (I agree with the answer overall though - the issue is easily fixed by leaving a comment.)
    – N. Virgo
    Commented May 30 at 9:23
  • 6
    @N.Virgo - and pretty much anyone who does watch the video will themselves have made an error in similar circumstances.
    – Jon Custer
    Commented May 30 at 13:36
  • 4
    Having a clear comment about errata is much better than for published books where the errata is on some not well known site.
    – qwr
    Commented May 30 at 15:51
  • 3
    I would strongly recommend this approach. Everyone makes mistakes; if you go out of your way to acknowledge and correct your mistakes you are demonstrating integrity and a commitment to truth - important values in math & the sciences, and academia writ large (or at least they should be!)
    – Anomaly
    Commented May 30 at 19:06

"Is it bad?" My first reaction was "well, it isn't good but it shouldn't be a big deal" and, in a way, I stand by that and am one of the 20 people upvoting David's answer, above.

But in another way .... It might be good. I can think of two good things about it:

First, you learned something. Not only did you learn what the right answer to the question was (that's not a big deal, you ought to be learning things like that all the time) but you learned to say "I don't know the answer to that, I will look it up. If you give me your email, I can send you the answer."

Second (and not quite contradictory to the first) you took a chance. You gave a talk that stretched you somehow. And, you made a mistake. Oops. **** happens. And it happens to everyone. Pete Seeger once said:

The only way to never sing wrong notes is to never open your mouth and sing. What a tragedy that would be!"

  • 3
    I think this is a great way to look at it. I'd stress that every presenter has probably made mistakes in off-the-top-of-their-head answers in Q&A sessions—whether they know it or not! These sorts of things are always best effort, and no one should be upset if an unplanned, unpolished, possibly unresearched answer to a Q&A question was wrong. Commented May 30 at 14:59
  • 2
    "you learned to say 'I don't know the answer to that'" - yes. Always better to openly acknowledge you don't know than say something you're not sure of. If you want a compromise, state your speculation with a heavy dose of uncertainty - "I'm not sure I'm remembering correctly, so I would double-check this, but if I believe [...]" or something.
    – Anomaly
    Commented May 30 at 19:09

If you can resubmit the video (you own a copy, you have the right to do that, ...) and really wat to fix your mistake, I would add to the video a caption with a star, and make the correction there.

I cannot find an example after having scrolled through a few I recently watched but will add a screen capture when I find one. Here you go:

enter image description here source: 3blue1brown | https://www.youtube.com/@3blue1brown

This only makes sense if you expect a large audience for that video. For reference, my keynotes in super big conferences got a tiny amount of views and proportionally fewer comments. If someone pointed out a mistake, I would have corrected it as a response to that comment, probably.

EDIT: another idea would be to cut sharp the original video right after the problem and inlay a commentary video if the explanation needs to be longer.
Something like "after integrating over the universe, we easily find out that the answer to everything is 43" CUT, then a short video of you telling "at this point a minor mistake crept in. After a careful review and a new calculation, I realized that I double counted the top quark so the answer is actually 42, which is more in line with the current literature" CUT and you resume the initial video.

  • 4
    Just a note that you can't "resubmit" a youtube video. You can delete the old one, you can edit the metadata, and you can upload a new one and mention it in the comments to the old one, but you can't modify the actual video once it's published.
    – lfalin
    Commented May 30 at 16:10
  • If you use YouTube studio tools, then the video can be edited "in situ" without having to submit a new version. That includes trimming, blurring faces, etc. However, there's no tool to overlay text on a video so that would indeed need to be a whole new version. Commented Jun 5 at 13:47
  • I actually think that the EDIT I did would be nicer than just the overlay
    – WoJ
    Commented Jun 5 at 14:32

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