Put this short video together showing good evidence for Russia having used military helicopters in Ukraine. Hidden in woods, at least 4 white dotted squares were marked out. Just 57 km from the Russian border, the whole area around the site, is a major hub for Russian led forces. Several large military bases and training areas are located nearby.
The squares are very large, measuring at least 15m x 10m. Coinciding with the construction of nearby military bases, they are seen from July 2015. By Aug 2016, they appear to have been repainted white again.
One advantage for the use of helicopters, would be the rapid transportation of wounded soldiers, Special Forces units and transportation of Russian military commanders.