It is not easy to find worthwhile Tai C'hi instruction. Most is New Age Armwaving and a large proportion of the remainder is the dishonest work of stage magicians promising to initiate their students into some supernatural art.
After studying with some famous folks (including Da Liu and Wm. C.C. Chen [both are armwavers, unfortunately]) and searching for over thirty years for a good Tai C'hi martial arts instructor I found Erle Montaigue.
If you are interested, see his website:
http://www.taichiworld.net/
It contains some articles which can tell you where he's coming from. For example:
Go to "New Articles" and click "Taijiquan & Self-Defence"
excerpt: "There is no ‘soft’ way to fight someone or to defend yourself. No possible way to defend yourself and not harm the opponent! However, how many times do you hear that Taiji is the ‘soft’ martial art that can be used to ‘gently’ put someone down."
or go to "New Articles"/"Rules For Fighting"
excerpt: "1/. Never step backwards. ...
4/. Never use two steps in fighting. ...
6/. Never use a lock or hold as your main fighting method. ...
7/. Never use pushes or pulls in self-defence. ...
9/. The legs are for standing, the hands are for fighting. ..."
And, yes, it is possible, not easy, to learn by videotape.
Good luck whatever you decide.
Bentley
Interplanetary Grand Poobah, Chi Ken Gua No - art of winning through retreat.