Many websites provide free download and conversion services. These websites can download and convert videos from popular video sites such as Youtube, Yahoo video, Google video, iFilm etc.  The following is a collection such websites.

KeepVID
http://keepvid.com/

KEEPVID supports 40+ online video sites, such as YouTube, Google, iFilm, Putfile,etc. It can convert online videos to FLV and MP4 formats with fast conversion speed, then allows you to the converted video from the site.

Vixy
http://vixy.net/

Vixy allows you to convert Flash Video (FLV) files to several popular formats online. It is using a compressed domain transcoder technology (outline in Japanese). It converts FLV to MPEG4 with faster speed and higher quality than a typical transcoder does.
Vixy can convert FLV to AVI/MOV/MP4/MP3/3GP

Zamzar
http://www.zamzar.com/

Zamzar is dedicated to helping you transform your songs, videos, images and documents into different formats.
The formats supported by Zamzar are:
Document formats :doc. docx. csv. pdf. ppt. pptx. xls. xlsx. etc.

Image formats: bmp. gif. jpg. pcx. png. etc.
Music formats: aac. wma. wav. ram. mp3. m4a. etc.
Video formats: 3gp. avi. flv. m4v. mov. mp4. rm. mpg. wmv. etc.
Compressed formats: zip. rar. cab. etc.
Non signup users can convert files with the sizes within 100 MB, signup users can convert 200 MB~ 1 GB files.
Zamzar also gives users the function to download video or audio from online streaming video websites;

mux
http://beta.mux.am/

mux is a website that can Convert video for download to your PC, Share video privately with friends & family and Send video to your mobile phone.
mux supports the formats below:

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