Advice for project

Question

hi,

my basic idea  to develope online video tutorial(like youtube) in asp.net in which user can login and logout. There is two side admin and user.Admin can upload his/her new video.

plz provide me advice

1)what should be best video formate shall i use (performance wise ,loading wise)

2) How can i save in sql r2

3) what datatype used in sql to stored video.

4)  most important key point from your side.