The hardest part of a specific music search is finding the song. Once it is located, there are many methods to convert it to any format you wish. Since the music is located, now how to convert it.
For example, if you use Firefox for your browser, there is a plug-in for Firefox that allows for "one click" downloads from YouTube. You can download audio only, or audio and video, into many different formats. In your case you could download the audio as an MP3. Then, there are many other audio converters that can take the MP3 and put it into a format that is compatible with Sound Forge.
If you use iTunes, it is a little more cumbersome. Download the music into your iTunes and then "burn" it to a CD. Then, there are several conversion programs that can "rip" the CD and convert the music to any format you want.
Now, all this being said, any "conversion" of the music will not be as good as an original copy. Quality certainly drops with each conversion program. The "best" audio sound would come from an original CD. But, if your main interest is using it for dancing, the quality should be fine. In my two methods, the best copy would be obtained by using the iTunes method because the source file is the best. Using the Firefox method, you don't know the quality of the original music that was used to create the YouTube video.
I have used the Firefox method many times for the studio. When we have a special "dance show" coming up (Holiday Show, Valentines Show, etc), the teachers always want some special music for their students. I taught the studio how to use the Firefox method to download from YouTube and then they upload the tune into iTunes for playing at the studio.
As far as the song goes, I am familiar with it and I have danced to it in several competitions. I do like it.