How to download and add music to a video file

I prefer to download/convert/edit/burn with Freemake Video Converter using a Windows operating system.

Downloading:
If the video site is not compatible with Freemake Video Converter, I use Freemake Video Downloader.
If the video is not compatible with either Freemake product, I use Download Helper on the Firefox browser.
When downloading any Freemake product from
www.freemake.com
I do not recommend getting the toolbar or any other extra software offered with Freemake products which you can avoid by choosing to customize the download and installation.  Be very careful which boxes are checked or unchecked.

Freemake can download youtube files and burn the files into a movie file onto a dvdr in a single swoop but I store these video files on my hard drive in MP4 format till I have a couple of hours to burn onto a single dvdr with Freemake.  Sometimes I edit these files and/or add music.

If I want to add my own music, I can choose *no Audio* when converting the file to make a muted MP4 file or I can add one long soundtrack using the dropdown audio menu.
If I have a soundtrack available (several songs already joined into one MP3 file), I can add that file to replace the original audio instead of muting the original.

(if ripping a DVD with more than one soundtrack or language, this audio dropdown menu may offer those additional options)

Sometimes before converting I trim out parts I do not want to do and/or break long videos into smaller segments or chapters, each saved separately

For music, I rip cds and more recently, online video files (youtube, amazon freebies, etc.).
RunHundred makes excellent song suggestions
http://www.runhundred.com/
Youtube has a zillion videos with music.
I just download with Freemake Video Converter by *Pasting the url* of the song on youtube as the source then convert to MP3.

To add music to muted video files, I use Windows Live Movie Maker.
I could add the music with Freemake but would be limited to one MP3 file. Plus it is easier to find the exact spot to change the song on Windows Live Movie Maker.   I save the movie for email which makes the file smaller cuz visual quality isn't worth more space to me.

You can also edit a video file on a dvd workout in the same way, ripping the video from the dvdr with Freemake.  Use the DVD as your source.  Freemake will give you a choice of titles to play, trim and convert.

ETA: when downloading and converting video files, make new folders as needed so you can find the files and delete files you no longer need.
For more tips, check the labels for Freemake Video Converter Tips or Freemake links

ETA:
To add MUsic while keeping the original cuing voice, do not mute the video before adding music with Windows Live Movie Maker.  If the original music is soft, you should hear just the cuing with your new music.  You can adjust the volume of the music files you are using with MP3Gain.
http://mp3gain.sourceforge.net/

Here's a brief walk through for adding music with Windows Live Movie Maker:
http://neverendingplateau.blogspot.com/2014/09/adding-music-with-windows-live-movie.html