Complex sentence: However, a standard videocassette ran for at least an hour at the highest-quality speed, while a Polavision cartridge contained less than three minutes of film, at a far higher per-minute cost than the finest videocassette tape.
Split into simpler sentences: However, a standard videocassette ran for at least an hour at the highest-quality speed. A Polavision cartridge contained less than three minutes of film, at a far higher per-minute cost than the finest videocassette tape.