Why do some professors arrange meetings to give updates about their ongoing work? The updates are certainly exciting, especially for the other people who have been in the lab for awhile and was involved in the work in some small way. But these meetings are also open to visitors, and visiting professors and post docs come too. Isn't there a fear of outsiders (or even insiders) scooping the ideas and beating them to publication? Although I highly doubt that, but I'm curious to know.
The main reason is to attract interest to their current and future work, in terms of both public interest and potential students, scholars, and postdocs who might want to work with their labs. Talks are a good way of accomplishing this. Research isn't meant to be conceived, designed, done, and published in a cloistered off world. Anyone who believes this shouldn't be in research.
If the point of research is to advance/exchange knowledge and to improve life, then it deserves to be made a public, accessible resource. Perhaps even work that hasn't been completed. It's important for researchers to be transparent about their work, rather than trying to hide it, especially when they accumulate so much funding, some of which often comes from public, taxpayer sources (i.e. government funds).
You might think visitors are outsiders, but it's important to keep sight of the fact that they likely helped fund the research in some way, and more importantly, that they're part of the people your research should be trying to help -- and there shouldn't be such distinctions on this account between outsiders and insiders.
Science is a human activity. There is no point in doing research if nobody reads it. Your research becomes relevant once you can engage with people. Bill Thurston has an essay on this, focused on math, but I believe it can be extrapolated to many other areas: https://arxiv.org/pdf/math/9404236.pdf
Professors giving Update , under an okay from institute /university / funding society is to be viewed in a positive way. Too often scientists have been criticised for working in splendid isolation (sometimes meant ivory towers ) and with lesser accountability to public at large. Ongoing research projects of a larger dimension and duation do require an internal review periodically ; this being made more open and transparent should not ideally invite objections. However , this is best left to professors themselves , as an option to share ; making a rule or compulsion carries am apprehension of becoming counterproductive. Prof ME Yeolekar , Mumbai.