The blockage we are talking about in the bug is of the first type.
It's
caused because various places in the FLV parser make small reads or
seeks of 1 to 12 bytes for various reasons, and this calls a read that
blocks media parsing (or something) until the next segment of data is
received. It's a design flaw in the parser, which really should get a
buffer to read and not attempt to seek outside it.
The reason it doesn't always stutter there is that the seek only
blocks
if it happens to be close enough to the end of the buffered data.