It was originally posted on the personal page of Igor Girkin on the Russian version of Facebook vk.com, which he has been using for months as his own personal propaganda outlet. He's still posting alibis over there with the incriminating post deleted, of course.
In it he clearly says that his forces downed "another AH-26" and even posts two video clips of the planes getting shot down.
It's deleted now, but nothing ever gets off the Internet once it's on there. If you think that that post was a clever photoshop, Google Cache has the original incriminating post archived.
If that's still not enough, or if you think Google is somehow working with the Ukrainians in a coverup, or got hacked by the NSA or something, even ITAR-TASS, a Russian propaganda organ still has a post up reporting on "eyewitnesses" that witnessed Russian rebels shooting down a AH-26.
If that's STILL not enough proof, or if you think that ITAR-TASS was somehow tricked by the CIA, NSA, NATO into reporting that a AN-26 was shot down less than an hour before the world realized it was a commercial plane, both RIA Novoski and Life News, again both Russian propaganda outlets still have reports up of an AN-16 being shot down over Eastern Ukraine a full hour before the horrific truth came out.