Problem putting transferring videos from computer to phone/facebook etc

[Racso_Ssor]

So I have these two videos that originally i took on my phone and ive since deleted them from my phone and put them on my mac but i want to put them on my phone so i normally do this by sending it to myself on Fb or another way that i know which both work.
However with these two videos it just gives me a grey screen? Any other ways to get it onto my phone, ive also tried changing the format which just made them grey with a few green flashes.
Thanks
(idk if this is the right place at al)

[Krispy Kritter]

I've never used a Mac or an iPhone.

In your screenshot, they are in the "pictures" folder, is that normal?

With Windows and Android, I simply connect my phone to the computer and copy the files where I want them. I thought Mac's were supposed to be easier to use?

[hech54]

HandBrake using one of the iPhone presets, then (I guess) iTunes to get it to your phone.
I use a different app to get video/music to my iPhone cause I detest iTunes.