First of all my apologies for my mistakeful English. I am using Youtube daily. So, please read the following fully.
If you feel the following is confusing, I have mentioned the very very basic style of navigation at the bottom of this reply which I was used when I was started to use YouTube with NVDA.
Open a browser and press Ctrl + L and type or copy and paste the below url.
and press enter key. It will open the subscriptions page to see the videos from the channels you have subscribed.
After the page loads, press D until you hear Main Landmark Today Heading Level 2
This puts you in the main part of the webpage.
Then pressing 3 key will help you to read the title of the first video and again pressing 3 key will read the next and so on. Pressing Shift + 3 will work in vice versa (reverse).
After moving the navigation to the video you like, press space bar key or Enter key to play the video. A new page is loaded and the selected video will start to play in the next page.
The Title of the video which is currently playing will be in Heading 1 level. So, pressing 1 or Shift + 1 will tells you the current playing video's title.
To jump to the current playing video's player controls, press D or Shift +d until NVDA says Main Landmark. Then pressing the tab key will change the controls to the slider, pause, mute, next, settings, etc. Shift + tab for moving vice versa. (Or B key to navigate by buttons such as play, pause, next, mute, etc.)
You said "When watching a video in Youtube, she used to move the mouse to the videos listed on the right side of the Youtube page and click on the mouse, to go to the next or another video. NVDA would read the content of the videos...".
For that see the following:
Pressing 3 will tell the title of the suggested videos (which is on the right side) one by one. Shift + 3 for vice versa.
Pressing Enter or Space bar will play that video.
If you feel the above was confusing, simply press H key or Shift + H key to navigate by headings (video titles). D or Shift D for Landmarks, B or Shift B for buttons such as play, pause, action, like, dislike etc.
Hope I haven't confused you much and I hope it will surely help you.
If you have any other questions, feel free to reply me (your brother). Thank you sir.