A free program for Android, by AndroTechMania.
This app allows you to play multiple videos at the same time in a popup window. You can even drag the player around the screen to put it in the best position for you. It can also play videos in the background, so you can do other things in the meantime. There are many options for you to customize the player. You can resize it, make it full screen, or even in a pop-up window. The player can be re-minimized at any time, so you can always see it. It can play all your videos in the format you want.
