I was thinking of putting a 2-3 minute video on my travel business webpage, showing the tours we offer etc. I thought this could be the centerpiece of my homepage. But I've never seen anyone do this before. Is it a stupid idea? Or should videos always be ancillary content on a homepage.

I guess a 2-3 min video is too much... but it would depend on your presentation...

With Flv compression in flash, adding a video these days is quite common. Flv compresses so small and loads so fast, I think it's very much so something that you could do.

Just make sure it's placed in a valid format.