In this paper we analyze how the frame rate affects the video perceived quality for different video contents. Combining these results with our previous work, a new parametric model is proposed for video quality estimation, including the effects of frame rates, bit rate, display size and video content. The performance of the new proposed model was evaluated for video clips coded in H.264/AVC at different frame rates (from 5 to 25 fps), different bit rates (from 25 kb/s to 6 Mb/s), and in different display formats, including VGA, CIF and QCIF. In total more than 670 processed video sequences were analyzed to derive the proposed model. The new proposed model is compared with other four recently proposed parametric models that take into account the frame rate in the video quality estimation, concluding that the proposed model has better performance than the other four.