How long is your stick, and are you doing the super traditional sweep, or side "swing" before you let loose?
Most likely, if you can cast a single hander, without much headache, you are just not utilizing the full casting potential of the Spey flinger. Don't try to mimic the video persay, just adapt the cast to work for you, in the waters you fish. I found that traditional Spey casts are suited to places where there is plenty of open space surrounding you. I can however, super shoot cast, small flies with a one hander quite easily, but I too have no real, legitimate skill when it comes to two handed casts, in the traditional method. As long as your final presentation is suitable, who cares how it gets out there. Purists will say one thing, but I say another! I also slam fish on very poorly presented Spey casts(fly presents, and sits properly, but the cast looks pretty haggared) for Bull/Brown trout in Montana, but then again, those fish have never seen artificial presentations, so they don't know any better! Good luck with your two handed adventures.
Look into Edward Ward, I have had many oppotunities to fish with him. Although we clean house with bait on the Oly Penn. he will still get into fish with fur, when it is a bait type of day. I don't know if you are familiar with some of the newer methods like "Skagit" casts, and another I forget, but named after an Eastern Russian region..Anyhoo, the more common skagit cast is very interesting, and makes for some very productive presentations, that fish can't not hook themselves when they strike. The only thing I can say about Ed, is that he is a total condition fisherman. When it isn't on fire for bugs he still produces, but he's still a bit off, when an old friend, Angie and I are slowly picking off singles with bait, or terminal. Great theories, and an overly publicizied persona, but still anyone interested in Spey flyin can pickup some good information. And he ties the craziest big bugs you have ever seen. Won't even go ino those big nasties, and where he uses them, but it is very interesting how he fishes none the less. He will never know the true potential of his creations, because he ties them for specific drifts on a specific River. Again, good luck, and don't be fooled that there is only one way to swing your bugs...