I'm new to coding and have been looking at how to make a custom 404 page and came across this :
It's helpful but instead of an image, I want to have a video background with a transparency filter.
Thanks in advance.
For the video you just need to use the HTML video, host the video file you want in the assets folder of your theme and reference it to the <video> tag.
The whole transparency thing is a bit unclear regarding how you want it to look like, nonetheless it'd be more complex.
Perhaps someone around here will be kind enough to dedicate their time to get it done for you but if it's an urgent situation you may want to reach out for a Shopify developer to get it done.
Yep, a gif would be easier because you can use it with the <img src="mygif.gif"> tag!