I can't say about all the 'Add-ons' but I have been using 'YouTube Downloader' successfully without any problems. This is an important feature as I can view and review downloads where ever I go where there is no Wi-Fi or no internet connection. I really like this and could sincerely recommend this Add-on as it works flawless. Thanks for this privilege. I am sure that I will explore the other Add-ons in the future as it becomes necessary. Thanks for this.