UserTesting.com - Usability testing has never been easier. Get videos of real people speaking their thoughts as they use websites, mobile apps, prototypes and more!
You-Get - Command-line utility to download media contents from the web
Instabug - The top apps in the world rely on Instabug for beta testing, user engagement and crash reporting.
CONV. - Convert YouTube video to MP3, GIF or MP4
Userbrain - Easy, fast, and affordable user testing for websites and prototypes.
Softorino YouTube Converter - Download YouTube video & audio. Watch and listen offline