Hey Pekka, I have looked at the original file. One thing that we don’t currently support is embedding sequences inside of other types of prims… so having a Sequence in the root, fine. But also having Sequences embedded inside of other prims, such as animations, causes problems. If this was something you intended to do, please let me know what you were hoping for and we can message this better to users… because obviously if this confused someone as experienced with Machinima as you are, it would confuse anyone else as well!
We have put more error and console messages into the next version of Machinima as well so more of these kinds of issues will be shown as soon as they happen. We will continue to add messaging to help you guys out, and where possible, we will just make the app do what you are expecting it to do!
I think if you remove the extra Sequence prims from this file you will get something which performs much better. Or, as you suggest, you could rebuild it. I find that each time I rebuild a project, even though I regret the time spent, I end up learning more efficient ways to do it.