oh, and .dat format also plays. While experimenting on what format was the smallest, I also tried .dat format and it plays. I now am going to convert most of my files to avi because with the AVS video converter I can change the perimeters and make it any size I want.
I think the reason that Hoster might have been having problems with the vids that I've been playing is because they are so large, but with the converter I can get them down to about the same size as a mp3+g made into a KMA (abt. 4-6 mb each)