Since the introduction of digital television, new services such as Video on Demand and IPTV have been widely deployed. These new enhanced video services are usually delivered via streaming technologies over IP-based networks to set-top boxes (STB). Unfortunately, such networks are commonly referred to as packet-based best-effort networks that cannot guarantee the correct delivery of the transmitted data. As such, network impairments like packet loss can cause severe visual degradations during video playback. Current existing methodologies for the subjective quality assessment of video sequences pose tight restrictions on viewing conditions and experiment duration. As a consequence, these methodologies cannot be used for the quality assessment of full length movies in real-life conditions. In this paper, a new methodology is proposed and used to evaluate the influence of packet loss and frame freezes on the perceived visual quality of full length movies.