NOTE: You have posted in the phone forum, but this is a tablet.
The SD card change over won't change if it freezes or not, and your tablet may actually not accept a SD card with that much storage. They do have limitations. The cause for freezing is usually due to to many things running at once, taking up resources, not space. So you would be better off making sure less is running before you go to watch the videos. The more you have running (even if you aren't actively using it) the more resources get used.