Hey Jon, nice job! Everyone starts somewhere, so I wouldn’t be too worried. I downloaded the youtube vid so I could frame by frame and offer some feedback. Here’s what I’ve got for ya.
Side Note: I think the camera angle you have is working against you. It's harder to see what's really going on. Starting out, I would highly recommend using a SIDE view to animate from at first and show us that. We'll be able to pinpoint any issues much more easily this way. FIRST step: - Anticipation! It's missing :D Every movement has even the slightest bit of anticipation before the move itself. Instead of starting from a dead still maybe do a slight foot shuffle or weight change before the step to anticipate the step forward. - I think the starting pose waist line is too high. Notice that both of the legs are nearly straight, leaving very little Y-axis to work with. Crouch him down just a bit more perhaps and spread the feet slightly. This would allow you to step UP into the passing pose then back down into the contact pose. - Every body part is moving fairly evenly here. Both hands, the front foot and the waist/torso are all moving forward staticly. Try and break this movement up a bit. Put the back hand behind him perhaps at the start or delay one of the arms before it comes up. - Your contact pose the back leg pops into a straight because it's hyper-extended. Adjust the waist so this pop doesn't detract from the fluidity. SECOND step: - I think the forward translation on the hips is too much, but its more likely a spacing issue over all. Remember that that as things speed up in animation or "ease out" the spacing becomes further and further apart. The same applies for the vis versa. I would highly recommend tracking the spacing of the hips and see if there is any irregular spacing. I use an arc tracker in Maya, but not sure if Blender has a similar feature. You can always use a magic marker in a side viewport on your monitor if all else fails. (ps. don't do this to LCD's though!) - Also on the second step, the back hand feels very rigid, probably because its the same pose. Try and break this up a bit by giving it a bit more movement, even if very slight. THIRD step: - The hips here don't make sense. As he's pushing off with his back leg he dips down instead of pushing up and landing onto the forward leg. Watch the arc there. - At one point both feet are off the ground making the character appear to float a bit. Make sure the front foot plants before pulling the back one off the ground. - Front leg hyper-extends and pops. Like before, try and adjust the spacing of the waist to prevent this, assuming the Rig has FK feet. The KICK: - I think this part of the animation is working the best right now. Although I would smooth out the part where the legs reaches the top of it's movement. Notice that the pose occuring right after is nearly a held pose with only a slight bend. What's happening is that it "feels" like he's hitting a brick wall at the top. Maybe put the previous frame with the leg lower so theres more cushion into the ease-out. - I think the kick is happening too fast as well. - Get the planted leg up on his toes perhaps as he follows through. This will portray the illusion of weight a bit more convincingly. - Finally, lets see some recovery! Right now the foot just comes down and it's over. I'd really love to see him come back down the perhaps look back up to see if he made the kick he wanted! In any case, hopefully this helped a bit :] Doing a full body run-kick is a very complex motion to tackle. I'm still tackling my blocking in stepped keys and getting it all feeling right is definiately proving a challenge. Keep up the good work and look forward to any revisions if you continue on with the animation!
ps. Definitely check out www.vimeo.com for uploading your videos to. It’s much better than youtube and allows anyone to download the file to frame-by-frame more easily.