How i can display in the excerpt of the video and links?

Hello to all. I am creating a new theme for my project. I have a few questions:

  • It is necessary to display a preview for the type of topic Link in topic list. What is the opportunity to do this?

image

  • Is there any way to display the topic video (youtube, vimeo, uploaded etc) in the topic excerpt? Or maybe I can display the excerpt with the full topic content with all html tags, which will be cut by the number of characters or number of lines? Look like this:

or this:

Or a simpler solution. If there is a video in the topic, it shows it, no, we show the image.

Maybe someone has already done this, I will be grateful for the help