The least private is to upload to YouTube and set the video private. then you can share the link. But if anyone guesses the link they will be able to see the video!
The easies but not very private is to share via Google Drive or Dropbox etc.. That way only your Provider (google or Dropbox etc.) can see the video
If your only concern is security and not cencorship use:
Cloud Providers - Mega.nz
This wont help you if there is an issue with spies or cencorship but it is easy and can be relatively secure. The uploader gets an account (the downloader can too if you want to be a little more secure) then encrypt the file with something like Veracrypt (create a container a little bigger than your file and send the password via email using PGP encryption) or just encrypt the file directly with PGP. Then upload to mega and share with your friend. If he has an account just add him if not you can share via link.
If your only concern is that only your friend sees the video but you aren't to scared by hackers then just share with mega without the added encryption. As long as both of you have an account on mega then the file should stay encrypted until it is on your friends computer.
If your concern is security and avoiding censorship and you don't mind a slow up-/download speed you could take a look at
It tunnels your traffic for the up-/download through TOR. One of you needs to get OnionShare and one needs the Tor browser. Then the one with OnionShare selects if he wants to upload or download and shares the link with the other, who can then open it in Tor browser (not any ordinary browser). Then one uploads the file and the other one can download.
This may take a while and both PCs need to stay on!
OnionShare is really only meant to be used if you have great security concerns or if there is an issue with censorship. Thats why many jounylists use it (e.g. Edward Snowden shared some data with Glenn Greenwald). So if you don't need the security and avoid cencorship you might want to look for something else.