[Double Naught Spy]

While a "good" shooting it appears, this video brings up a valid tactics & training scenario that could have ended much worse for the officer.

All such violent encounters experienced by officers could have ended much worse for the officers.

Officer 1 deploys a taser that is rendered ineffective by, most probably, the thick jacket of the suspect. The suspect then turns and makes a move with his 3foot bar toward the officer. The officer does NOT have out his gun and is rendered defenseless as he seems to struggle to pull out his gun in place of his non-lethal taser.

The officer is not rendered defenseless. Just because you cannot inflict immediate harm on another does not make you defenseless, though this is definitely a mindset oft repeated on gun forums.

While the officer struggles with his gun (as you noted), what is he doing? He is retreating, keeping space between himself and the suspect. That is an active defense an impact weapon wielded in such a manner. He may not be able to stop the weapon, but where you see the officer as rendered defenseless, by keeping himself away from the suspect, he has rendered the suspect's weapon ineffective.

What if Officer 1 did not have immediate back up when arriving on the scene?

Then he would not have opted for less lethal weapons.

Should officer 1 have had his gun out and ready alongside his non-lethal taser, in case WHAT HAPPENED actually happened?

NO! First of all, he was protected by his fellow officer. Secondly, having a non-lethal stun gun or pepper stray in one hand and a firearm in the other hand can result in unintentional discharges from the weapon not intending to be used due to sympathetic bilateral reflex.

This became an instance where lethal was necessary over non-lethal and had officer 2 not been right there, it could have been potentially very bad for officer 1.

Yes, but officer 2 was there which made possible the attempts at less lethal methods first. It could well be claimed that in any situation where one officer renders assistance to another officer that the encountered could have turned out much worse for the first officer without help, but the officers were using team tactics because they were both there. Officers usually don't employ team tactics when they are alone.