You can also report the players from your game history or by looking them up in-game. All reports go to Bungie security, so it doesn't matter where you submit them.
Personally, I find that reporting them in-game is a lot faster and easier. It only takes about 10 seconds or so to report the player this way.
oh I did..... just figured I'll throw the evidence down.... pics... vids... even the evil hatemail... got called the n word and harassed when I'm simply trying to enjoy soloing iron banner....😔
You don't need to provide additional evidence. Bungie can see everything from the in-game data. I doubt Bungie even accepts videos and screenshots because those can be manipulated. Fully aware the report forum allows you to send in additional evidence, but I doubt it's looked at.
Just report them in-game, block them, and move on with life. That's what I do, and I regularly get thank you messages from Bungie, [url=https://i.imgur.com/OZlioBQ.png]such as this one.[/url]
If you don't want random players sending you messages, then I recommend setting your communication settings to friends only. You may also wish to do that on your platform settings.