Yeah it might not have much of information in this post, it's more like asking friends "man, do you have this problem ?" because, I don't know why a layout that literally contain just 2 of an official Touch plug-in and a Video plug-in in the layout that point to a correct path to the mp4 and webm files, are working with Dropbox but not in Itch.io,
so I searched the C2 documents and I found something about MIME types, and I think, "hmm this might be it". But I'm not sure because, I don't have any knowledge about it. and C2 didn't create a "video" folder for me so that confused me even more. because, I believe in C2 standard.
Yup, you're right, unlucky me most of the time my posts are not in the spot of the helpful user.