Yes it is possible, and I do it a lot.
Most websites I use allow the video to be on top of all open programs, so I can place it over my EU screen while playing. Also youtube video's do a lot of good while crafting.
note - I always play in window mode to make this happen.
*edit* I even run other video games (a bit laggy) at the same time when I'm crafting in Entropia. Hunting is not very good with that, as I tried it before and failed.