You can play all the right notes with a perfect technique, they will sound horrible without a good sense of rhythm. Rhythm placement is everything and this lesson should help you develop some nice improvisation ideas.
The secret to playing with a nice rhythm feel is to divide the strong beats into smaller rhythm segments. Let's start with sixteenth notes. As you are listening to the backing track, mentally sing to yourself sixteenth notes throughout your improvisation. The rule here is to play on the sixteenth notes.
Make sure to be comfortable with the scales before improvising. The track is in A Dorian and will also work with an A minor pentatonic.