CrashPlan is our favorite backup tool for Windows, for the Mac, and we've even shown you how to build a bulletproof backup solution with it. CrashPlan gives you the flexibility to back up any folders you select on your computer (or whole drives, if you prefer) to external hard drives, other computers on the same network, a friend's computer across the internet, or online to CrashPlan's own servers, where it's stored and encrypted to keep your data safe. The backup utility is set-it-and-forget-it, and it runs quietly in the background whenever you're away from your computer, or at specified times of day. It's smart enough to only do differentials and incrementals, and supports multiple backup destinations so you can back everything up at one time everywhere it needs to go. Restores are just as easy, and a few clicks drops all of your files right back where they should be. You even get access to your backup data on your mobile devices. If you have a ton of data to back up or restore, you can even have CrashPlan send an external hard drive to your house that you can back up to and use to seed your first backups or restore from, all without blowing past your ISP's bandwidth limitations. You can read more about CrashPlan's features here.
5K Player also features DLNA server playback so videos you grab can be watched on any devices on your home supporting DLNA network; it supports AirPlay for quick playback to supported devices. Pick a video in the library and you can do a quick conversion to MP4, MP3, or even ACC (an audio format preferred by iOS devices). The player didn't like playing back the overly large 4K file though and experienced buffering issues—VLC didn't have any problem with the same file. Ultimately, there's a lot to like about 5K Player, from the price to the features, especially if you look at them as extras on a downloader. But the interface and playback issues may have you looking elsewhere.
Third-party software is where you will get the best control over downloading online videos. Typically, you paste the URL for the YouTube video you want into the program, and it downloads the highest quality version it can find. For videos in 1080p High Definition (HD) format, that's usually an MP4 file. For anything higher in quality—4K and even 8K videos—the file format is typically MKV.