Sonarr is based on RSS feeds - explicitly designed for this purpose of getting new updates from subscription-like sources. This is much lighter in processing requirements. I’ve also tried to make this UI as similar as possible to the other *arr apps for familiarity.

Index an entire channel/playlist or get “older” videos. Subarr’s RSS approach is specifically for “subscriptions”: new video is posted, take some action Media management. Once Subarr kicks off the post-processor (like yt-dlp), its job is done. Use Plex/Jellyfin/etc or another one of the linked solutions above if you require more control over your media