For HD Videos >= 1080p: Directly save videos in 4K/HD quality online is hard, but you can free use VideoProc to save video/playlist from 1000+ sites in batch and original quality. Convert, edit, record and more.
To download videos online without installing any software on your device:
Downloaded videos are too long? This tutorial shows you how to freely clip videos in any size and format. You can also cut, trim, merge, crop, rotate, etc to polish videos.
Here's the easiest and fastest solution to extract subtitles from videos as SRT, ASS files in 3 simple steps. You can also import or search subtitle for the videos downloaded online.
Want to enhance the quality of the videos you shot or downloaded online? Here’re many solutions, such as upscale 360p/720p to 1080p, stabilize shaky video, reduce video noise, etc.