you might try doubling that given that your file size is 33megs, but I assume that once its uploaded something is trying to either convert or compress the file similar to the way wordpress does when you upload a file.
128megs was enough for me on my system when uploading up to a 15 meg jpg image so you might need a little more..
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Sounds like poor coding to myself, a good script would not require excessive use of memory. You could try increasing it to 512MB as a test, though, not something I would highly recommend.
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