@Ministryofgiraffes.. Oh by all means keep the long one for yourself and your loved ones but it is a proven fact that you lose viewership once a video gets longer than 4-5 minutes. People just can't stay focused. Most videographers really struggle with getting rid of shots because they have an emotional attachment to them.
@SSC-uba It helps to have a friend/ SO help because they will tell you which shot is better when you have multiple shots of a subject. Keep clips to 3-5 seconds (more on the 3 end) unless it is a really amazing behavior or shot. Another really popular thing to do is make mini - vids with single subjects/sites/behaviors (like Mantas etc.),... people really like those as well. Here is a link that you might find helpful or interesting:
How to Shoot Amazing Underwater Short Video Keep up the great work!