Online Video Converters

Checked out the 2007 article Top Ten Online Converters - Freakitude, and four of them still work:

"1. ZamZar: Free Online file conversion service. It can convert your online videos to a number of video formats. The converted files are sent via email.
2. Tubefish : Tubefish video converter can convert your videos instantly to MPEG, AVI, MOV, 3GP and Divx.
3. Movavi : Movavi is another online video converter. It notifies via email when converted files are ready to download."

Here are three more,  from 13 Useful Free Online Video Converters | Flash, Design, Vector, Photoshop, Adobe Tutorials |
  1. Converts or downloads Youtube videos to MP3, MP4, AVI or MPEG.
  2. You Convert It "Convert any Youtube and other Online Video to popular formats or download the video without buying or installing anything on your PC"
  3. Tubeminator: Download and convert from any site. FLV, AVI, MP3, MP4  
This is by no means a comprehensive list, but it will definitely get you on your way!