Sometimes there is no video, only audio. Need reboot

Sometimes when I try to watch an episode or a movie there is no video, just audio. I discovered if I reboot my Pi, then I can get video and the program selected plays normally. What can be the cause?

Please upload your logs, otherwise we can only guess at the problem.

Most likely your gpu_mem setting is too small for the skin that you are using resulting in the GPU running out of memory for some videos, however log files should pinpoint the cause.

Where do I find the logs? I did not change that setting. I don’t know what it is or what it should be for Confluence skin.