QuickTime is crashing when saving or exporting

I see that this is a common question over the years, but the answers don't seem to be ones I either understand or think apply to my case. I have been working in a few videos that I recorded myself, snipping them into segments and exporting them for about 2 weeks. I did one snip and save tonight and then Quicktime crashed and I haven't been able to save or export since. Any help for me please? This is happening tonight on both my Macbook Pro 10.10.2 OS X Yosemite and my iMac 10.10.3 OS X Yosemite.

I appreciate all suggestions. Thanks very much.