Cameras battery dies. What happens to video?
Let's say the battery dies or you take it out while recording what would happen to the video?


Why can't you try it? Just start video recording and remove battery.

As I can see, you have camera using DV tape, so you will nothing lose of the recorded data.

If you have DVD camera, sdcard or HDD, things get worse, as you must "finalize" recording. In case power loss with HDD/sdcard, you can lost few last seconds/minutes or whole file. Some cameras writes temporary .dat files, which can not be played. But it can be repaired. Sometimes it's no easy, but it's possible to get back your data. I can't say anything about DVD, as I not expert in this area. So, just do experiment!