YourTube is a mod, that will add extra functionality to the native YouTube iPhone App. By installing YourTube, the mod will add a new tab on the bottom bar by which you can access a Download Manager that will allow you to download YouTube videos in High or Low quality, without using MxTube.
The app will be available in Cydia, and there isnt too much info about it right now, but it seems it won’t be free. The mod will be available as an MobileSubstrate extension which means YourTube will be integrated without using too many resources.
From the screenshots below, it seems that the process is pretty simple: tap on a video and choose the High Quality (recommended if you use a WiFi connection) or Low Quality (EDGE/3G network).