Smart ForTwo 2007 engine knocks

Good day together, I’m thinking of buying a Smart ForTwo (no MHD) with 71 hp and 129,000 km. Today I drove a great smart sample, only the engine sounded a bit strange and knocked. Since I’m not a smart expert, but at the same time I know that the 3 cylinders in the Smart can sound rough, I would be happy if a connoisseur could watch the video in the attachment and tell me an assessment. Also I would like to know if the 129,000 km (permeable checkbook) are easily contractable for the small engine. Because find little Smart Petrol with over 150,000 km at mobile.de Many thanks for the valuable support. Marius