I'm aware that a lot of people have uploaded this already, however, I have looped it for your listening pleasure, and will try to do so with more themes. Thanks to eventhubs for uploading the picture and theme.
Everything in this video belongs to Capcom and/or Marvel.
I've been working on a Vanilla Street Fighter IV Trial Guide, which can be downloaded from the link found under "website" on my user page. It covers more than only the trials, it also has in-depth descriptions on various executional things in general. Here's a sample:
"How to buffer simple stuff:
Knowing how to buffer is extremely important, and you probably won't be able to clear even all the normal trials without knowing how to do it. The rule of thumb is: DP moves are easier to cancel from a standing move, and QCF moves are easier to cancel from a crouching move.
Buffering Charge moves: When buffering charge moves, make sure that you are charging before you have to do the move, so that you have enough charge when you have to activate it. Always charge Down-Backwards if possible. If you're doing horizontal Charge Moves, you can charge in the directions "UB~DB". If you're doing vertical Charge Moves, you can charge in the directions "DB~DF". If you're using both horizontal and vertical Charge Moves, or a Charge Move that requires you to charge DB, Like Guile's Super and Vega's Scarlet Terror, charge "DB".
Cancelling a standing move into a QCF move: There's not really an easy way to do this, just be fast. s.HP xx Hadoken with Ryu: "s.HP, D, DF, F+HP". It IS possible however, if you're going to cancel a standing kick into a QCF+P move when you have no QCF+K move or vice-versa, to press "D, DF, F+K, P". Of course, this is also true for DP and HCF moves.
Cancelling a standing move into a DP move: The easiest way to do this is, if you do Ken's s.HP xx HP Shoryuken: "F+HP, D, DF+HP", or, as this combo uses the same button for the normal move and the special move: "F+HP, D, DF+NE HP". There's a problem with this though, and that is...
Cancelling a standing move into a DP move, when you have a forward command move on the used button: What would happen if you tried the above combo with Ryu? He would do Solar Plexus Strike, his f.HP command move, instead of s.HP. So what do you do? Sadly, there's not much you can do, other than be quick. I recommend "s.HP, F, D, DF+HP" or "s.HP, F, DF, F+HP"
Cancelling a crouching move into a QCF move: Shouldn't be a problem, just do, if you're doing c.MK xx Hadoken with Ryu: "D+MK, DF, F+HP"
Cancelling a crouching move into a HCF move: This is only done once if I recall correctly, in Rose's H Trial 5. There, you have to do c.MK xx EX Soul spark. Here's how to do it: "DB+MK, D, DF, F+PP"
Cancelling a crouching move into a DP move: This is rather important, because a lot of people have a problem with this. All examples will be Ryu trying to do c.HP xx HP SRK. Here's what people usually do:
SUPER COMES OUT INSTEAD OF DP: You probably tried to do: "c.HP, F, D, DF+HP" and ended up with "c.HP, DF, F, D, DF, F+HP". If you want to do it this way, make sure that you do not press forward the last thing you do.
HADOKEN COMES OUT INSTEAD OF DP: You want to do "c.HP, F, D, DF+HP", but you do "c.HP, DF, F+NE HP, D, DF+HP", so that the Negative Edge when releasing HP triggers an Hadoken before you can do your DP.
My recommendations: There are two good ways to cancel a crouching move into a DP move:
"F, D+HP, DF+HP": Here you press forward, then you press down+HP, triggering the c.HP, and then quickly DF+HP again. If you use this one, you're starting to buffer the DP move before you do the crouching move, which makes it easier to do slowly.
"F, D+HP, DF+NE HP": This is the same as above, but having Negative Edge trigger the DP. Obviously only works if you're trying to cancel the crouching move into a DP move using the same attack button.
"DF+HP, D, DF+HP" or "c.HP, mash D, DF, D, DF, then HP": Here you use the DF, D, DF shortcut to buffer the DP. The first one is controlled, and very effective, the second one is useful if you have to cancel into the DP after a long combo. Just be careful so you never press F, because then super will come out. It doesn't matter if you're holding D or DF when you press HP during the mash, input leniency makes it work anyway. You can do a Negative Edge version of this as well."