Did you also get all the old user content? Like old videos and pics from halo 3?
And if yes, where can we download our old videos/pics?
No. Nothing from old fileshares is available on Halo Waypoint. They are only accessible in game, so unless you have a capture card or know someone willing to record them for you, there is no way to download them.
If had Bungie pro and rendered your videos you can still download them from your file share on halo.bungie.net.