Help with cropping videos

[Loving my Oldies]

I’ve been taking videos for various reasons but have found it an excellent way to show the vets what is going on at home with dogs and their various ailments and age related issues.  

 

However, they are generally too big to forward to anyone.  I’ve worked out how to shorten them, but I don’t really want to do that and was wondering whether there is a way to crop them to make them smaller the same as a photograph can be cropped.

 

Grateful for advice...... but please talk slowly and clearly and in words of one syllable       as I am a bit of a numpty with regard to computer speak.   

[jemappelle]

Maybe look at compressing them using an app.  This will make the file size smaller.  If you Google 'compressing (ipone/Samsung/etc) videos' you will find some apps.