Add (1080p, 720p etc) instead of Best, Worst etc.

Add quality levels to downloadable videos. For instance, say the best quality is 1080p, so Best gets you 1080p. Normal would be 480p & worst could be 360p. What happens if you only want 720p.Paste in the Url, then allow user to choose their preferred bitrate quality.

For online music, when pasted url is put in.

As an example: https://www.youtube.com/watch?v=ANygbRCuwZo

Allow an option to only download it directly as an audio file (mp3 etc) at a selected bitrate. No need to convert it from video to audio first.

Basically take a look at something like Ant Download Manager for inspiration. Paste in a URL to their prog, watch the options that come up (allow you to choose bitrate, format, audio only etc & all without converting first), then add a similar method into your program.