Basic Tutorial 13 is broken

Hi,

Thanks for the work on this set of libraries, impressive work :)

When I try to use one of the provided example tutorial binaries, it successfully runs but is non-functional. In particular it seems like seeking is has no effect. I've been able to confirm the issue on both mac and linux (ubuntu), I'll need to build gstreamer from source to confirm if the issue is also present there.

The command I ran:

cargo run --bin basic-tutorial-13 --features=termion

This successfully runs, opening a window in which the video is streamed. However, when I press either S s or D to change the video speed or direction, the video is unaffected.

I'll attempt build GStreamer from source tomorrow to confirm that the same example in C correctly functions on my machine, however maybe you have an idea of what could be going wrong here.