I think screen-capture should be the top-level tag, with the other two as synonyms. Why?
- Another name for a screenshot is screencap (short for capture)
- They both deal with taking copies of what is currently on screen (one video, the other photos)
- Screenshot is used for two different reasons currently:
Changing screenshot to be under screen-capture would help mitigate it's use as a meta-tag, and allow requests for handling any type of screen recording/capture to fall under the same roof.
The top-level screen-capture wiki excerpt could be something like:
Questions should use this tag when asking about methods of taking pictures and video in certain games or platforms