That's definitely not the way the video camera works. The only limits are:
4K video at 5 minutes.
Any video at 4GB.
MMS very small, usually less than 1MB, but dependent on your carrier MMS limit so varies by carrier.
You've got some kind of problem. Maybe a SD card problem if you are saving there or maybe some app you installed or something else interfering. Clear data and cache for camera app. Clear cache in recovery. If saving to SD, change to phone storage.