The add-on is meant to improve download performance, and that’s about it. There are no preferences to tweak, no button to click, no UI to interact with. Just use Mega as you did normally and you will find that files are downloading faster. Do note that the extension does require a browser restart after installation.
We tested the extension by downloading an 80MB file and compared the download speed against Chrome, and also against Firefox without the add-on installed.
Compared to Chrome, Firefox with Mega Extension installed downloaded the 80MB file 15 seconds. The difference here can be considered small enough to be overlooked, especially due to variations in internet speed. The real difference we noticed was when we downloaded the same file with the add-on disabled. Download time for the same 80MB file went from 2 minutes 33 seconds to 5 minutes 17 seconds in our Firefox with add-on vs. Firefox sans add-on test. The difference here is obviously major, and the improvement is significant enough to warrant installing the add-on.
What the add-on doesn’t do yet however, is allowing downloads to go through Firefox’s own download manager before they are saved. Chrome does not handle downloads from Mega from its own download manager but once a file has finished downloading, it is logged in Chrome’s own download manger and can easily be opened from it.
The add-on also claims to let you “batch-download an unlimited number of files without any size restrictions from MEGA”. It isn’t clear what size restrictions are placed on the downloads since even bandwidth limit for a free Mega account has not been disclosed. Our tests showed that when downloading multiple files, they were queued for download rather than downloaded simultaneously.