I'm giving 1 star only, because the developer of this add-on wants to deceive users.

1.:
This add-on DOESN'T support downloading 1080p videos for free. You have to pay for that.

2.:
When you try to download an 1080p video with the free version, you'll get the following message:
"Converting these streams to downloadable formats for you needs powerful server infrastructure, therefore 1080p/mp3 downloading has been limited to PRO users."
This is an obvious lie, since downloading these videos doesn't need third party servers at all, but it's a good excuse to harvest some money from the unsuspecting users.

Other 1080p youtube downloaders use ffmpeg on the users' computer to merge DASH streams together, so there is absolutely no point using third party servers for that. That's the safer, faster, cleaner and cheaper option, so don't get yourself scammed.