I may go insane if I can't solve my space and glitch issues.  I have dumped and sent lots of material onto external hard drives and yet my computer still lacks sufficient space.  My third show (Holiday show) is completed and refuses to download smoothly.  3 quarters of the way through I experience green lines and jumping.  I believe my imovie program is saying too many edits, however the episode is only 8 minutes long and last month I completed a 22 minute documentary successfully and it downloaded nicely to youtube. Is it a puppet conspiracy?  I tried downloading straight to youtube rather than going to Itunes first. It was better but one irritating green line prevailed.  Because I need to get this show posted this week, there may have to be glitches but I really don't want that after all the work involved.  Any thoughts?

Have you 'Finalised' the project in imovie? (in the "file" menu) Sometimes imovie cops a snot if there are lots of cuts and you have dumped clips from your machine. Finalising sometimes tidys it up. That's about the length and breadth of my ideas... Good luck though, "computer says no" are the most frustrating issues ever... 

I never use iMovie so I'm afraid I can't help you.  But I just want to say that reading the words 'cops a snot' followed almost directly by a Little Britain quote made my day.

I hope you get your issues fixed soon.

What do you mean as far as finalizing.  I re downloaded again for the 20th time and it was a bit less snotty, however I would like it snot free.  At least it isn't jumping between scenes like a strobe light like it was yesterday.  I thought someone slipped me something.

I had the same issue of strobing just today with Final Cut when I played the film in the timeline.  I saved it, closed the program, and then reopened it and all was fine.

I discovered that if you go to the top menu bar (file) and select 'Finalising' what the imovie program does is kinda iron and smooth out all the clips. What I mean by that, is that it gathers all your clips together and makes it one contained file. You wont see any difference, but the software metaphorically 'ties all the strings together'. You may have taken a clip from here, a clip from there, and finalizing almost 'collects for output' or puts all the eels in one jar. imovie can then export or 'share' it without having to expend so much memory reaching throughout your program to render it all. I'm not great at explaining technical guff, but give it a go and see if it helps. It can take a while, but it may mend the issue. All I can suggest after that is some kind of sacrifice to the Apple God? I hear destroying anything with Bill Gates name on can work...

I tried to finalize but it shut my computer down.  I researched it and when you finalize, it does it in all 5 formats taking up more space.  I probably will have to call tech support.  I'm down to one segment with a green line.  May have to live with it for now.