I hear 'starea' in both versions (fast and slow). Is this how an 'a' should be pronounced after an 'r'? Or ist it just the way this partikular speaker speaks?
The á is a long a, its duration is longer. The r does not matter. I suggest you to read the Tips and notes about Czech pronunciation and orthography.
Where can I find those?
Use your web browser and click on a skill. Then clisk on TIPS or on a lightbulb.