Instead of downloading media to your iPhone you can use Tonido iOS (https://itunes.apple.com/us/app/tonido-file-access-music-vid...) app to play/stream pretty much all the video formats directly from your PC, Mac or Linux (or) you can use the app to download the media and play with VLC.
Actually many users do want immediate gratification. Don't want to wait for the media get transferred to the device and play. Also there is an issue of storing large file in your mobile device and delete it afterwards.
I am a Tonido user. I am not affiliated with them anyway
(and I can only assume you are involved with Tonido, given that half your HN posts are promoting using it)