I haven't watched the video yet, but all I can say is thank God it's not another moon. Also, are you using a mod to get increments of 100 in factory build orders, or have I missed a key?
You can see what's being built by a factory in the bottom left tooltip. It was a laser platform. Why do people build tanks? I don't see any reason to do so when bots seem superior in every way and speed is so important in this game. Even if you want to go for levellers why build more than one tier 1 vehicle factory? EDIT: watching 103 it's like you anticipated my question EDIT2: 103 was definitely a great game, and a good example of what PA looks like right now I think.
Ants do more damage and have more health than bots for around the same price(bots are a bit cheaper iirc). The way I think it's supposed to be done is to get them blobbed up outside your enemy's base, then send the bots in first to soften up/distract the defenses/defenders and then the ants just roll in and steamroll what's left. Doxes are annoying and can do damage, but if ants get into your base it's basically GG, they just destroy everything so quickly.