Assuming you talk about submitting a new run: You need to upload the video of the run to an external video-hosting site (preferably YouTube, or Twitch if you are streaming). Then put the link of the video from that site in the run submission form.
Are you talking about the run submission form? That is where you put the URL for whatever video hosting/streaming site the run of your video is hosted at; you link to your run so the moderators can verify it.
Please note: some games don’t always require video proof (although it can be rare to see this) so check the rule for the game/category you ran and verify that your run and video meet any and all requirements.
@Miner24 please try to not bump old threads but
Upload your video file onto a file/video hosting service. YouTube is normally preferred since it is easier to retime runs there. In some games, videos off of YT don't get retimed at all, retimed incorrectly, if runs on YT are timed correctly anyway; or are rejected
Once it is uploaded: find the share button, copy the link and paste it into "Video link" on SRC
@Crazymonkycrazy I have a video on every step of the submission process if you are having troubles. Just use the chapter guide to navigate to the portion of the video that you need:
