these are not in portage Reproducible: Always Steps to Reproduce: 1. 2. 3.
Created attachment 51016 [details] gst-plugins-mpeg2enc-0.8.7.ebuild
Created attachment 51017 [details] gst-plugins-mplex-0.8.7.ebuild
Created attachment 51018 [details] gst-plugins-xvid-0.8.7.ebuild
all these, + the one in portage works perfect on amd64, i suggest keyword amd64.
these are best left in your own overlays until any packages require them.