dear Dominic,
I agree with my colleagues that a good assessment cannot be done with tshirt on. I would like to see this person in (short) shorts only. A video analysis is only part of the assessment and can assist but...
- better light is needed,
- more steps are needed.
I would like to see him standing on one leg for at least 30 sec and see how his whole body reacts.
Better even, can he go to a real gait lab? that would be the best....
However....I do think using you-tube is a smart way of getting information all over the world fast ... very good idea!
good luck with your assessment