Board Thread:The Panopticon/@comment-28743561-20180307013354/@comment-188432-20180525193625

I personally don't hear it as anything other than "million". And if you blow up the image on a really big TV and look at Baker's mouth, he really doesn't seem to be making a plosive b with his lips. So it both looks and sounds like an m to me.

But let's give the tiebreak to the novelisation, where page 25 reads:
 * The Doctor produced a pocket chronometer and studied it. ‘A long time after your period. Two million years or more.’

(I also think that this is a good use case for preferring a DVD run through a decent sound system over the YouTube clip. Audio on YT is frequently too noisy to clearly hear this level of detail, particularly when talking about older episodes of Doctor Who.)