Archived for reference:
http://archive.is/iEoOWCan you record a video with screen-cast of the telegram?
1. Scroll the messages up and down several times.
2. On record close the telegram and reopen it and
3. again scroll up and down.
Do the scrolling slowly so that we can read the contents.
Have the video unedited. And upload it in Youtube or any other video hosting service.
If you do not have the telegram in your desktop the learn how to use it in desktop and then do the recording.
Also can you prove that the telegram ID is his? Remember: Telegram username can be changed.