The reason their progress had been so bad in the eight years since 2014 is because in Donetsk and Luhansk Russia was using mainly the local Ukrainian separatists plus some "Russian soldiers on holiday" (their actual explanation).The thing about one of the clips there that blows my mind is that that's Donetsk airport! They've been fighting in that same area for years, it's crazy how in some parts of the East it seems like Russia has barely been able to take much ground!
The big problem with this was that if you're a Ukrainian of Russian descent and you look at your country and see how it's westernising and moving towards closer ties with the EU, then you look at the Russian Federation and see how it's worse off now than it was under Yeltsin, and then you decide "yeah, our region needs to secede and join Russia" then you're a complete goddamn moron, and having a "rebel force" made entirely out of complete goddamn morons with a few actual soldiers to organise them is a recipe for many things but success is definitely not one of them

Need I remind everyone that the Donetsk/Luhansk forces are the guys who posted pictures on their official twitter account of the new Buk SAMs they had acquired, then shot down a military transport with them, then publicly bragged about it, then shot down a Boeing 777 with them because they were too stupid to tell it apart from a military jet, then deleted their previous tweets and denied ever having any anti-air weapons, and genuinely thought that would work.