[gentoo-user] Unable to downgrade media-video/ffmpeg-0.10 using package.mask

[Chris Stankevitz <chrisstankevitz@gmail.com>]

Today portage upgraded ffmpeg from 0.7.8 to 0.10.  I do not want to
the new version (0.10).  I attempted to indicate this to portage,
using 'man portage' as a guide, by changing package.mask:

  crs-m6600 ~ # cat /etc/portage/package.mask
  # Avoid dealing with deprecated functions that break SimLib
  >=media-video/ffmepg-0.10
  crs-m6600 ~ #

Portage, however, appears unwilling to downgrade me back to 0.7.8:

  crs-m6600 ~ # emerge -p ffmpeg

  These are the packages that would be merged, in order:

  Calculating dependencies... done!
  [ebuild   R    ] media-video/ffmpeg-0.10
  crs-m6600 ~ #

Note: I have tried two additional representations of ffmpeg in
/etc/portage/package.mask:
  >media-video/ffmepg-0.7
  >media-video/ffmepg-0.7.8
but still portage will not downgrade me.

Q1: Why did none of my three ffmpeg mask attempts cause portage to
downgrade me from media-video/ffmpeg-0.10 to media-video/ffmpeg-0.7.8?

Q2: What is the proper way to tell portage to not upgrade me past ffmpeg-0.7.8?

Q3: What is the proper way to tell portage to downgrade me from
ffmpeg-0.10.0 to ffmpeg-0.7.8?

FYI: I am trying to avoid ffmpeg-0.10 as it removes a public function
I am using elsewhere.

Thank you,

Chris