So I thought I'd share a tutorial of how to do this because I didn't see it anywhere on here. It's pretty simple and all you need is a WebM video and a hex editor. Lets get started!
Step 1:
Get a WebM video that you want to upload and open it up in your hex editor. I like to use HxD as my hex editor of choice.
Step 2:
Find the first appearance of thehex values "44 89" in HxD you can press Ctrl-F and search for those hex values.
Step 3:
After you find those change the bytes after 88 to the following "88 40 B0 70 B0 00" your end result should be something like this.
Step 4:
Then click save as and save your video. When you play the new video your video player should think it is only 4 seconds and it should continue playing even after the 4 second mark.
Step 5:
Open TikTok in your browser, sign in and click the upload button. From there upload your TikTok and it should be the full length video if you did everything right. Post it and you just uploaded a video that's longer than the max time allowed.