Gurgling/knocking sound?

I'm sorry the video seems not to have loaded in either post. With that temperature it would be hard to say but it could be something like a water pump that the impeller failed on. But the loud knocking makes me worried without hearing it.

No problem. The rattle under the hood sounds like valve noise, however it's hard to tell for sure as noises are hard to pinpoint because the engine block causes them to travel. I would start by using a mechanic's stethoscope and listen to the engine to determine where the noise is coming from. If you don't have one a section of hose or tubing can work. You hold one end by your ear and then move the other end around until you find the loudest point of the noise you are looking for. That should at least narrow down the possible options. However, it sounds most like a valve problem. The interior squeak sounds like an issue with the blower motor. Try turning the fan speed up and down and see if the squeak changes speed to match. If it does it's likely that the blower would need to be removed to see if it's the motor or if something got into the air ducting and into the blower. If you don't have the tools, I would suggest having a shop look it over. Noises are one of the worst things to locate without physically examining the vehicle, and even then, they can be misleading.
Site policy wants us to treat each issue as a separate item to allow for better searching, If possible, could you create a new question about the squeaking interior, do the speed test and post those results in that question. Thank you.