There was some discussion on another forum that there was an issue with #1 engine and that the whole thing was inadvertent. I'm not sure if there was any solid info behind that though you can see that #2 is producing the expected smoke trail but #1 is not.
Except he appears to be yawing right, unless you think he's stepping too hard into the good motor, which he's not as the rudders are both centered up if you check it in slo mo. I think both motors are just fine hence the rejoin on lead after the shennanigans.
That was pretty amazing, but? Why couldn't they trim off the first 30 to 40 seconds? Would surely not detract from the clip, and would probably save thousands of hours of viewing time as people click on it...
You can get a sense of what may occur when you see the dust clouds being created by the exhaust deflecting off the ground. So you know they were very low even before the one split off. Plus it seems its always difficult to pick out the aircraft on a video. After multiple viewings it became easier to recognize the aircraft further out. YMMV.
Definitely looked like the port engine was not running. Lucky the Flanker has a really good T/W ratio because it looked like he barely made it. Compressor stall on go-around has to be really fun.