Wow, I started doing pantographs because I found them so much easier and faster than custom quilting. Seems to be the reverse for so many people here. The video from SewCraftyGirl is exactly how I do pantos. It never would have occurred to me to do anything, regarding trying to stretch the design to "fit" the quilt top. The design just naturually runs off the top/bottom & sides of the quilt, wherever it falls. That's the purpose of a pantograph in my opinion.
NOTHING to be afraid of. The most important things to keep in mind are - keep your movements steady and smooth. If you wander off the line, don't panic, just gradually move back towards as you go along. No one is going to be comparing your end result to the panto paper, so don't fret about following it perfectly. Smooth lines are more important than exact tracing.
Always start and end with a partial row - by which I mean run the pantograph pattern off the quilt at the top and bottom (and sides) so you have a continuous design all the way to the edges. You'll have cut-off bits of the pattern, but that's OK.