I have a 27" iMac and am trying to run video in one window of Safari while doing work in another on the same screen. Is there any option for having that video be the full browser window (yet not the entire screen)?
Depends on how the video is playing (what plugin it's using) but you can just hit [Command]+[N] in safari and open a new window that will be able independently enter full screen (or not) as you wish.