If I only have mobile how do I edit a timer on top of a recording?

So when I was looking at the rules, it said that pictures would usually be accepted when submitting a run (though video is recommended and required for world records), however when I go to the “submit a level run” page it only says “video link” and doesn’t allow the option to access my camera roll (I’m on mobile). Is there a way to fix this or do I need to post the picture on a website to create a URL for the image?