That second video is pretty good. Keep in mind that a freshly killed animal in the field is going to be a lot bloodier and you aren’t going to be able to see that well. Most times you can cut down through trachea and esophagus as demonstrated, then feel for the lymph nodes under those. They’ll be smooth, relatively firm and semi-round, tucked tight against the neck. They will usually have a little fat attached to them like the video shows. If it feels squishy or has lots of little lobes, you’re probably in salivary gland or fat. If in doubt, cut it open. Should be light tan to gray, smooth and shiny, and kind of resembles a piece of cooked mushroom to me.
If you’ve already removed the head, I find it easier to start at the cut end of the neck and just cut forward towards the head, separating the trachea and esophagus from the spine. When you get to the first cervical joint, lymph nodes should be right there, tucked against the muscles on the dorsal (spine) side. If your head has frozen, the samples are still fine. It’s just that the tissue gets a lot softer and lymph nodes get more difficult to recognize.
For disinfection, we generally put non-disposable tools in 10% bleach solution for an hour. That works, but not all equipment can tolerate that kind of abuse.