Complex sentence: Initially a purely photo-sharing service, Instagram incorporated video sharing in June 2013, allowing its users to record and share videos lasting for up to 15 seconds at a 640x640 fixed resolution.
Split into simpler sentences: Initially a purely photo-sharing service, Instagram incorporated video sharing in June 2013. During its launch in June 2013, videos were limited to 15 seconds maximum and a 640x640 fixed resolution.