I recently found LosslessCut (https://github.com/mifi/lossless-cut) that is basically a GUI for ffmpeg, you can make simple edits without re-encoding the stream.
git blame shows only who made the last change. Maybe that person only changed the name of a variable, applied a codestyle change, moved a function declaration to another file or many other things that the change was almost irrelevant to the code behavior.
There are a few options that help you out with this:
-M Detect moved or copied lines within a file
-C In addition to -M, detect lines moved or copied from other files that were modified in the same commit.
--ignore-rev <rev> Ignore changes made by the revision when assigning blame, as if the change never happened
--ignore-revs-file <file> Ignore revisions listed in file