Battery power is still OK, after playing video content for three hours?
Does the "freeze" make the iPod non-responsive, so that you need to do a Reset? If it is just the playing video that is affected by the freeze, and the iPod does respond, you may still want to d a Reset (if you have not already)
A Reset is like "rebooting" the iPod. It is not erased.
If that does not help, the next step would be to do a Restore on the iPod in iTunes. The Restore button is on the iPod's Summary screen in iTunes. This will erase the iPod, re-install its software, and set it to default settings. If data corruption on the iPod's storage or a software issue is the cause, a Restore should fix it.
It is also possible that there is a hardware-related problem with your iPod's hard drive. It is freezing when trying to access a certain portion of the hard drive.