A common (and easy to make) mistake in this video. The yellow flexible gas connection is not Corrugated Stainless Steel Tubing which is a completely different product used as gas piping with or instead of hard (black) steel or copper gas pipe. That yellow tube is called a Flex Connector. Flex Connectors cannot be used like CSST and are specifically designed to connect a gas appliance to the main gas line.
The rust in the blower compartment is an indicator that condensate is leaking (or has leaked) from the flue. Condensate must be controlled and, if condensate can leak out, CO might also leak out. Often, we can’t operate the furnace long enough to determine if condensate is still leaking. That is a call out for correction by a HVAC tech.
I’ve made several of these kind of videos and it is hard to get them perfect. Without exception, I see things in my videos where I groan. I say good job Julie!