It's not difficult. Download the You Tube ap to your phone. Create an account. Close the ap.
Once you have shot the video, close that ap. Open the You Tube ap on your phone and press the '+' button at the center bottom. Your videos will appear in the media ap on your phone. Select the newest video and then follow the prompts for title and description.
After it uploads and you are watching it, click on the 'Share' tab under the video display. Copy the link.
Return here and click on the film icon at the top of the reply box. When that window opens, paste the link you copied into the box and select OK, or Done, or whatever it says. Then you can add more text in the reply box or just clixk on Post Reply.
It is not at all as complicated as it looks on 'paper'. Once you have a You Tube account this all takes about 10 seconds plus the upload time of the video.