I have a BlackBerry Curve, which can be used to watch YouTube videos online with Bolt Browser, but the effect is not so good, since the GPRS speed is low and the player is bad, what is more, I want to keep some videos, thus I often download the YouTube videos in 3GP format, and watch them on my BlackBerry without pause.
Below 10 web apps are the best among those I have tested, some of them are websites, some of them are Firefox add-ons, and some of them are mobile websites. Besides 3GP, they are also available to download MP4 format videos.
1. Easy youtube downloader

Easy youtube downloader lets you download the YouTube videos in FLV, MP4 and 3GP formats. Besides visiting the web page, you can also install the related Greesemonkey script to download the videos directly on YouTube website.
2. Gazzump

For free account, you can download 4 videos a day. Besides 3GP and MP4, Gazzump also lets you download YouTube videos in MP3, WAV, FLV and other formats.
3. KeepHD

You can watch the YouTube videos on KeepHD, and the videos can be downloaded in 3GP, MP4 or FLV format. The MP4 quality is quite nice, but the 3GP quality is not good enough.
4. KeepTube

KeepTube lets you download YouTube videos in FLV, 3PG and MP4 formats.
5. YouTubeKeep.com

YouTubeKeep.com also lets you download YouTube videos in 3GP, MP4 and FLV formats.
6. YouTubeTo3GP.com

Just Input the YouTube video URL, and then you can download the video in FLV, 3GP, MP4 or MP3 format. By the way, as you can see from the above image, the process bar maybe not workable, though you can still download the converted videos from YouTubeTo3GP.
7. Zamzar

With Zamzar, the YouTube video can be converted to many formats, such as 3GP, MP4, RMVB, and so on. But you need to input your email address to get the download link.
The above 7 web apps are websites that let you download YouTube videos in MP4 or 3GP format online for free, besides, there are also some Firefox add-ons for you to do the same things:
8. Video DownloadHelper

Video DownloaderHelper is a famous Firefox add-on, which is not only available to download videos from YouTube, but also nearly from all other video websites. If you want to download the video in 3GP format, you will need to install an extra desktop software on your computer.
9. Easy YouTube Video Downloader

The Firefox add-on Easy YouTube Video Downloader lets you download YouTube videos in FLV, 3GP, MP4 or MP3 format easily. The download feature will be displayed behind the YouTube video embedded code.
Go to Easy YouTube Video Downloader
The above 2 Firefox add-ons let you download videos in MP4 or 3GP format on YouTube website directly, and you can also download YouTube videos in MP4 or 3GP format on your mobile phone directly with below web app:
10. Cupish.com

Cupish.com is only available for mobile browser visit, you can search and download the YouTube videos in 3GP or MP4 format, as well as watch them directly. By the way, there will be “CUPISH.COM” added in the downloaded video, and large videos are not available for download, but the quality of the converted video is quite nice.
Among the above 10 web apps, I mainly use Video DownloadHelper when at computer, and use Cupish.com to download YouTube videos on my BlackBerry directly. Which web apps do you used? Or do you have any other nice web apps to download YouTube videos in MP4 and 3GP format?
Related free web apps:

2 Comments
Dooclip site provide direct download, visit http://www.dooclip.net you can chose videos format (mp4,3gp,flv) for download
YouTubeKeep also lets you download in high-quality FLV, HD and Full HD now!