[osx] - re-enable yadif deinterlacer

Users suggested we have year 2014 and macs should be up to the task of using yadif deinterlacer. Since we have this enabled for the other platforms we should get it in sync (i don't trust ios hence the kept exclusion.

Up to the RMs its as safe for helix as adding it ;)

note to myself - needs a rebase before merge (tomorrow evening earliest)