Interesting, I never had those connotations myself but see it repeated a few times in this thread

When we set out to put together our media plan / SEO we researched all the varieties of keywords / etc and were surprised to see how far out ahead "webinar" is from "online meeting" / "online seminar" / "screen sharing" / etc

eg:

http://www.google.com/trends/?q=webinar,+online+meeting,+onl...