What's been notable about some of the footage coming from Qusayr (mainly via the Qusayr Media Centre and Tariq al-Homsi Youtube channels) is that despite reports of civilians being allowed to leave by the Syrian Army via a safe passage in the north of the city before the fighting began it seems many civilian remain in Qusayr, either through choice or circumstances, for example this elderly couple, and this group of women and children
This has resulted in inevitable civilian casualties, including injured and killed children (graphic), with a video showing their burial posted yesterday
It's also worth noting that currently it appears the northwest quarter of the town seems to be the main source of resistance against the Syrian government forces, which has long been the main stronghold for the opposition in the town going back months. It's possible that rather than holding territory they were unfamiliar with the Syrian opposition forces decided to stick to the area they were familiar with, and this could be why we're now seeing what appears to be very slow movement on the front-lines compared to rapid movement early on in the battle.
Syrian Opposition Fighters (Including Abu Sakkar) Appear In A Video From Central Qusayr