You just made me listen to a lousy of several videos worth of 30mins. playing time and I didn't see the problem you described. There's many possibility that can caused the interuption, unstable internet connection, slow connection, too many running processes on the device...etc...
And one other think i should mention that even though the video is running on seperate window and you can multi-task while playing video in background but it is still a child widget of the one that launched it. If you clicked that back arrow icon on top right of the window that you played the videos it will destroy the videoplayer window, you can still click on the video item to launch the video info screen and back out from it without closing the player. Also if you click play on another video while the videoplayer is opened or playing, it will tell the player to start playing the new video. Oh you didn't say if it stopped playing or the player was destroyed.

About your question on xtube ..I do not have time for it now, and there are still some room for improvement with this app. I do not plan on adding a bunch of feature which come with a bunch of bugs, I rather perfect the existing one and then move on to the next.