I have tried two night sky time lapses now in LR Time lapse 4 and Lr CC and both TL's rendered with the first third pixelated than smoothing out and finishing fine?

here are links to the two TL's on V

1) https://vimeo.com/126738995

2) password "rez" https://vimeo.com/127988948

any idea why this is happening? I am basically following along step by step with the tutorial.

thanks

Looks like a problem with the vimeo complression.
What settings did you use in LRT for rendering?