I use the browser as a task/data aggregator and prefer tabs to bookmarks. Usually, I open a tab, work with it, discard it (or entire session), then open it again in the same state as I left it. Additional tab extensions help me manage thousands of tabs and make my browsing experience comfortable and efficient. So, for example, instead of downloading pdf-file and saving it to the file system or saving it as a bookmark, I find it easier to open it in a separate tab in a special place in the tabs' tree hierarchy, read a little, and then leave it "hanging" there for a couple of years until I need it again. Also, whenever possible, I try to use web versions of applications instead of their desktop counterparts (whatssapp web, telegram web, web calculator, web calendar, etc).
Recently I've faced a challenge to transfer the entire book (fb2, epab) and video (mp4, mkv, avi) library from the file system to the cloud. And it would be nice not to download these files from the cloud every time I want to watch them, but to open and keep them in browser tabs. Unfortunately, Firefox's native capabilities to handle some file formats are quite sparse. I also didn't find any decent addons or web services.
My question: is it possible to use desktop applications, that work with these formats, and display them in(as) tabs in the browser? Suppose I could use the VLC interface to watch video without leaving the browser window and AlReader interface to read books. Maybe it's possible to display any desktop application as browser tab?