l am a beginner fly fisher, and when l try to cast the fly does not extend fully but instead the fly line falls on itself and the fly falls on the bunched up fly line. When l watched this video: http://youtube.com/watch?v=t2SgcCw6I8M&feature=related
l noticed that his fly line extends in a straight line. Mine does not. What am l doing wrong?
Also, how can l shoot as much line as the guy in the video does?

Shorten up your line. It is a matter of momentum. There must be enough energy in the line going forward to carry both the line and the tippet forward. Either your line is too heavy, you do not have enough juice in your cast forward, or the tippet is too long.

Sometimes it helps if you find someone who already knows how to fly fish to watch you and tell you what you are doing wrong.that is how l learned - then l started going fishing for bluefill before l moved up to trout.

l agree with Joe. The chance to have a patient, experienced fly angler coach you through your casting would be invaluable.

FYI, when you cast a fly rod, energy is stored in the rod (i.e., the rod is ''loaded'') during the backcast. That energy is transfered to the line during the forward cast. If the rod did not ''load'' sufficiently during the backcast, there wo not be enough energy to unfurl the line during the forward cast and lay it out completely.

My 2 pence, put some tension on the line in your hand just before the line starts to touch the water. If you cast without any tension on the line and the line touches down it will pile up.

Here is a MUCH better video that will help you to improve you casting, watch all three episodes and it should be of help, obviously without actually seeing you cast its not as easy to tell where you are going wrong, if at all possible why not hire a casting instructor they can help you out allot
http://youtube.com/watch?v=kLfJBTctA4Q

e.b. made a very good point about the back cast, most casting problems l have witnessed or fixed have stemmed from a poor backcast.

Try letting out 20ft. of flyline (no more than that) & smartly take it back to the 2 o'clock position. As u r doing this, glance over ur shoulder: u should see the flyline ''load'' the rod, when the line is fully extended backwards, come forward in a fluent motion, stopping at 10 o'clock, the line should lay out nicely for you.

Keep practicing w/ 20 ft until u r comfortable then try 25, 30, etc.

10 and 2 with sharp swift movements