How to get HQ youtube thumbnails?

Depending on the resolution you need, you can use a different URL:

Default Thumbnail

http://img.youtube.com/vi/<insert-youtube-video-id-here>/default.jpg

High Quality Thumbnail

http://img.youtube.com/vi/<insert-youtube-video-id-here>/hqdefault.jpg

Medium Quality

http://img.youtube.com/vi/<insert-youtube-video-id-here>/mqdefault.jpg

Standard Definition

http://img.youtube.com/vi/<insert-youtube-video-id-here>/sddefault.jpg

Maximum Resolution

http://img.youtube.com/vi/<insert-youtube-video-id-here>/maxresdefault.jpg

Note: it's a work-around if you don't want to use the YouTube Data API. Furthermore not all videos have the thumbnail images set, so the above method doesn’t work.

You can simply get HQ youtube thumbnails..

http://img.youtube.com/vi/YOUTUBE_VIDEO_ID/hqdefault.jpg

Are you referring to the full resolution one?:

https://img.youtube.com/vi/<insert-youtube-video-id-here>/maxresdefault.jpg

I don't believe you can get 'multiple' images of HQ because the one you have is the one.

Check the following answer out for more information on the URLs: How do I get a YouTube video thumbnail from the YouTube API?

For live videos use https://img.youtube.com/vi/<insert-youtube-video-id-here>/maxresdefault_live.jpg

- cornips

YouTube resolutions and images

http://img.youtube.com/vi/<video-id>/<resolution><image>.jpg

Resolution
- lowest resolution
sd - Standard Definition
mq - Medium Quality
hq - High Quality
maxres - MAXimum RESolution

Image
default - Default image (1, 2, 3 shot from video, or custom uploaded)
1 - First shot from video
2 - Second shot from video
3 - Third shot from video