Fortunately I found an answer on the Ubuntu forums. Install: ppa-purge package in a terminal with a long scrollback buffer (so you can manually reinstall what fails to reinstall automatically after the purge) sudo ppa-purge ppa_gstreamer-developers/ppa This should be documented on the gstreamer-developers PPA homepave, but if it is I sure couldn't find it! IMHO the uninstall instructions need to be at least as prominent as the installation instructions. My advice is to think twice and carefully before installing from a PPA! <blockquote style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;" class="gmail_quote">After "upgrading" using the Lucid PPA (<a href="https://launchpad.net/%7Egstreamer-developers/+archive/ppa" target="_top" rel="nofollow">https://launchpad.net/~gstreamer-developers/+archive/ppa</a>) my gstreamer is totally hosed! The most fundamental stating point for my application no longer works at all: gst-launch v4l2src ! video/x-raw-yuv, framerate=\(fraction\)30000/1001, width=640, height=480 ! xvimagesink Setting pipeline to PAUSED ... ERROR: Pipeline doesn't want to pause. ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Device '/dev/video0' cannot capture at 640x480 Additional debug info: gstv4l2object.c(2093): gst_v4l2_object_set_format (): /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Call to S_FMT failed for YUYV @ 640x480: Invalid argument Setting pipeline to NULL ... Freeing pipeline ... How do I revert to the stuff in the repos that at least mostly worked? </blockquote>