... Perl will tend to hang onto memory, figuring if you used it once you will use it again....so tell the system to keep it allocated as yours, even though temporarily it is idle space

...and if you try to run a resource heavy video driver from your main program directly, it will bog down and become unresponsive...thus the IPC

.. the display basics are this....iirc gstreamer will launch in it's own window, but i can't recall how many controls they give you...like stop ,start, rewind, go to frame, etc. .....so you can embed the gstreamer output into one of your own windows, where you can include buttons and enties for control ..... you will have to read the gstreamer docs and examples ( the c library ), and google for gstreamer tutorials

... see Perl/Tk front-end to mplayer for a Tk app which would do something similar....however, Wx is a different program...but it should give you some control ideas