To clarify my above comment, please refer to point 2 of the Budapest Memorandum.
Unless I've misunderstood something, the Right Sector organisation turned Russia's commitment not to use force against Ukraine into a license to mistreat people who were pro-closer ties with Russia.
And if the other agreements are broken, such as the US trying to influence the democratic process, that nullifies the agreement anyway.
Of course Russia did because they want to control Ukraine and keep it in their 'sphere of influence'.
Looking at
"Ukraine on Fire" again, at 28:10 (see also the preceding few minutes) Putin says "We said, 'of course, if Ukraine has come to this decision (to have a trade agreement with the EU), this is it's choice and we respect this choice. But we don't have to pay for it' ". He's refering to the fact that the two countries already had a unique economic relationship, thus the EU deal would leave Russia's customs border wide open to EU goods without any negotiations. Yanukovich and co. realised that they would lose this economic relationship if they signed the agreement with the EU. If this is true then it means Russia was willing to let Ukraine go, but that would not be economical for Ukraine, as it would lead to a trade barrier between it and Russia.