Welcome to Android Central! In general, since your question is off topic from the original post, it's better to create a new thread rather than post it in this thread. But to answer your question, the best way to share large videos is to upload it privately to YouTube or your Google Photos in the cloud, then share the link with the recipient.
If you're trying to send a video over MMS (i.e., the text messaging app), there is a maximum filesize of about 1 MB, so most videos will either be too large to send, or will be severely compressed. Google Messenger can send larger videos, but I'm not sure if there's a filesize limit there as well.