I'm quite new to Adobe Premiere and I'd like to get an answer for my problem:
I made new sequence in AP from the 20MB .flv file. How is it possible that after exporting it with the FLV codec and "Match source attribute" preset it becomes a 60MB file?
Because, "Match Source Attributes" has nothing to do with bitrate settings. If you want the exported file to be same size byte-wise, make sure your bitrate is more or less the same for both video and audio as the source file. If you're not sure what the source file's bitrates are, use a product like MediaInfo to find out.
Thank You very much