We have introduced 2 separate api for youtube app lover, search and download respectively.
Search endpoint will be used to extract youtube video detail like author, video url, videoId, title, keywords, thumbnails. averageRating, dislikeCount, likeCount, viewCount, description etc… we are providing list of matching video detail by free text search or video url, channel url, playlist etc.
Download endpoint will return result with all available download options like format, audioEncoding, bitrate, itag, size, url, videoEncoding, videoQuality, framerate, resolution, etc…
Note : url will have fixed expiration time, so after certain amount of time it will not work and needs to get new url again
If you wants to merge video and audio in file then use ffmpreg utility to generate one video file.