Great link Hilly, very amusing. I bet BR would approve of the running shoes on page 12.
"Unfortunately, there will always be people who will laugh at you while you are running backwards. Sometimes, if the conditions are right, they will even boo you". Ha ha.
Doing backward running drills are no brainers for boxing and American football because they both involve moving backwards during competition (NFL defensive backs and QBs). I used to do backward running drills when I was serious about my tennis for coordination and warm-up purposes.
I would guess that for it to be that beneficial for quads and therefore knees you'd have to do a fair bit of it - too much to be an efficient use of time.
I haven't tried it for running but admittedly one of the weaknesses of running is that it doesn't develop any allround athleticism and that everything is done in the sagittal plane.
I'm going to incorporate backwards running into my drill routine, at the start of recovery runs and add in the backward skipping on the down portion of hill repeats and report back. For me it seems more appropriate for a drill exercise than anything else. It's not really backwards running but carioca step drills can also be a good drill to do.
The world record for backward running the 800m is 2:31.3!
http://www.recordholders.org/en/list/backwards-running.html