How to include proof of when a video was made, something that couldn't be be faked at a later date?
There isn't any way to do it within the video.  You can easily prove a video was made (or altered) after a particular time, but you can't prove that it happened before a particular time via the media itself, since you could edit things in from previous time to make it look that way.

The non-video answer would be to generate a signature of the video file and get it cryptographically signed by a reliable time stamping service.  This would prove that the video files had been unaltered since the time the stamp was applied.  Most Certificate Authorities can do this.  I personally use StartSSL because they are pretty cheap but reasonably well respected.  

Alternately, you can have a document from a notary about when the video was made, though that won't prove it wasn't altered in some way.  The notary may have more legal baring than a particular CA's time server though depending on if anything causes a loss of faith in the Certificate Authority.