You can try changing the model's light reference with another object off screen.

http://www.youtube.com/watch?v=adh2i7UNCtU

The motion editor is good for high level manipulating, such as noticing you have an arm too low during a scene and you need to raise it after key framing. Instead of having to go back and change all the keyframes you can select all of time and move the arm and the curves will move with it.

Easiest way is to export as .smd, using Blender or Maya and the SMD Tools.

https://developer.valvesoftware.com/wiki/Blender_SMD_Tools_Help

I don't know what exactly you're trying to animate, but I could possibly help.

If you're just wanting to paint on a skin, you can use Gimp or Photoshop. If you actually want to put a model onto the player rig, you'll need either Maya or Blender. GCFscape can open vpk files, you just need to go into the options and select it as a filetype for it to open.

I've never had any trouble exporting as MP4, the only times I've had any kind of problem was back before they had decent codecs installed.

What export settings are you using? It sort of looks like a bad codec.

These are reskins of TF2 characters that are material replacements. If you make copies of the TF2 models and put them in usermod or some other game directory and then put these materials with them that's the easiest way to do it. Otherwise you will likely have to go through Blender or Maya and then export them as a Source Model, which means you'll likely have to rig them.

Otherwise you need a decompiler that works with Rift Engine models.

You'll need to modify the material file so it can accept paint. It's fairly straight forward.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=153130138

Its easier to loop a walk in Maya, but you can copy the keyframes and paste them to the last key in the sequence. You'll have to adjust the forward movement axis so he will continue to walk forward at the same rate.

I would call it choreography instead of animation because that's what it is. You're moving through a pre-determined set of moves that are being fed into some kind of software that imposes the moves onto a model. Though it is animation in the sense that you are taking an inanimate object and bringing it to life, but there needs to be distinction between the various ways of getting to that point. Mocap is cheap, fast and easy, keyframing is expensive, long and hard to master. To be honest I don't like wathing mocap movies made with SFM, they just feel cheap even if the movement is nice. It becomes acting at that point.