This paper proposes a model for estimating, at the decoder side, the distortion induced by the transmission over an error-prone channel, when error-free reconstructed frames are not available as a reference. The proposed estimation model considers explicitly the temporal error concealment algorithm adopted at the decoder. In the evaluation of the induced distortion, we model the effects of the absence of motion vectors and prediction residuals in the decoding process. In addition, we take into account the error propagation along successive frames. Experimental results conducted over real video sequences coded with the state-of-art H.264/AVC video coding standard validate the proposed model. In fact, the distortion estimated when no reference is available is strongly correlated both at the frame and group of pictures level with the actual distortion. This technique represents an effective no-reference video quality monitoring tool that can be embedded in any H.264/AVC compliant decoder.