To help in the discussion of the ASL/English wikipedia I have made a sample (http://simple.wikipedia.org/wiki/Clerc). The hand icon there is there to indicate the paragraph is signed. Click on the number one after it to go to the page with the signing that is housed off the Wikipedia site. The deaf adults and students who have seen this are ready to start building more as they see it as a very valuable and accessible tool for acquiring information.
We all believe you already. That's not the issue here.
Videos could be stored on the Commons and linked to from the English text page but the video file size limit would need to be increased dramatically from 2MB. The sample video in the link above is about 1.5 minutes and is 16MB.
I hope you realise that 16MB is a lot of space just for one article. At that rate, just 1000 articles will vastly deplete server resources. The Sicilian Wikipedia reached over 2000 articles within less than a year of its creation. If we expect the same of an ASL Wikipedia using streaming video, the space and bandwidth requirements will be astronomical.
Making Wikipedia able to handle video will make it more up-to-date. Text and pictures were top-o -the-line in the '80's.
Wikipedia is already able to handle videos. Small videos. Like a video of hands clapping, or of fireworks. Not videos that are 1.5 minutes long.
To reiterate an earlier point. ASL is a natural language and deserves a Wikipedia like any other natural language. The users of ASL are bilingual in ASL and English to varying degrees (some totally fluent in both, most more fluent in only ASL) and the languages influence each in the deaf community. ASL has many signs borrowed from English orthography. There is no common ASL orthography. Attempts at using SignWriting and other orthographies have not caught on even after 20 years.
You're actually wrong here, surprisingly enough. There are plenty of ASL users from Mexico who know no English, also from other countries where ASL is used but English is not taught to most deaf people.
Mark