Changing WinAmp from/to windowshade mode causes video window to resize. Why?

I have a television hooked up to my computer via an S-video cable. When watching video from my computer, I use Winamp v2.91 as the player. I move the Winamp video window over to the television screen and maximize it. This results in a full screen video on the television, but not on my computer monitor. I find that if I put Winamp in Windowshade mode (“small” mode, which you get by double clicking the top bar of the player, where it says “WINAMP”) or if I go out of that mode, the video window on the television suddenly becomes very small, and I’ll have to double click it to maximize it again. What’s going on? How do I prevent this from happening?