@ Daniel, sorry mate, there are better videos but they keep getting taken down off youtube (understandably).
Hamilton was given orders to let Alonso pass him at the start of Q3 (when they were waiting at the end of the pitlane waiting for the session to start, Lewis was 1st, Alonso was 2nd and Kimi was 3rd). the team wanted Lewis to let Alonso go into the lead. Lewis drove away and he felt that if he slowed to let Alonso pass, Kimi would also pass him, meaning he (Lewis) would have to slow to make a gap to Kimi so he could run in clean air, which would lose him precious time in the session. Lewis felt that Alonso wasn't close enough to him, so didn't think it was reasonable for him to slow and let him through. he apparently disobeyed a direct request from Ron Dennis to let Alonso through.
then when it came to the final couple of minutes, Alonso pitted first of the 2 McLarens for his final set of new tyres and final quick run. Hamilton knew Alonso was getting his tyres changed so was slow in the pitlane so he wouldn't reach the pitbox too early so wouldn't have to sit and wait for a long time. with about 1min 48 seconds left, Alonso had his tyres changed and was released (the lollypop was raised). for whatever reason, he waited an extra 11 seconds before leaving the pitbox. Alonso crossed the line with just 2 or 3 seconds of the session left, meaning he could do a final lap (which was his pole lap).
Hamilton, because of the delay in the pits where Alonso just stayed there, didn't reach the line before the session ended, so couldn't do a final lap which he was supposed to do.
Alonso says his engineer told him to stay there, counting down the seconds on the radio before telling him to go, apparently in an attempt to join the track in clear air.
speculation is that Alonso decided to stay there by his own decision, or with the help of his trainer (the guy on the pitwall who is highlighted in the above video i posted), in an attempt to "pay back" Lewis for not letting him pass him at the start of the session like he was requested.
the bone of contention is that if he was supposed to stay there, the lollypop man would not raise the lollypop, he would have been told to keep it down until the engineer counted down 10 seconds (or however many seconds was required to get him into clear air), and then told him to raise the lollypop to release Alonso, which is what happened earlier in the qualli session whenthe lollypop stayed down until it was the right moment for Alonso to be released from the pitbox.
Ron is sort of blaming both drivers, Lewis is blaming Alonso for holding him up and staying in the pitbox unnecessarilly, and Alonso is blaming Lewis for not following orders from his boss.
make of it what you will.
RIP Jules, never to be forgotten. #KeepFightingMichael