The links you’ve noted are different, but they point to the same resources. The difference is that the RPM Fusion page makes you use a mirror URL which will redirect you to a mirror close to you, while the other URLs are using the RPM Fusion download server (not sure if this redirects to a mirror either). In both cases, though, you will receive the same file.
This is no different than the below. The shell sees “\” as a continuation character at the end of the line and continues the command by reading the next line as well.