moving clouds can be really fascinating!!!
what is the sudden flash at 13" ? did you change settings or is it the script's fault?
Speaking about movoments of clouds, you can have different reasons for clouds moving in different directions.
1) Clouds being carried by contrasting winds (such as in your case)
2) Clouds "shifting" through wind, for example: the wind blows in E direction, trying to carry the cloud away, but the cloud dissolves when carried away to E and re-creates from the W margin. So, the cloud fragments move towards east, but the cloud appears to be stationary (and perhaps even to "climb" against the wind in West direction). this typically happens in correpspondance with some feature (usually a hill) that changes that status of the air above
Just a few days ago I took a (normal) timelapse that has really chaotical movements!