Phase detectors (202, 204) in a progressively scanned television receiver measure the phase of the receiver video speed-up memory read (8 fsc ) and write (4 fsc ) clocks with respectto the double line-rate horizontal sweep signal (FB) of the display. Delay means (34, 36) are provided for delaying the video signal recovered from the memory (30, 32) as a function of the difference (224) between the read and write clock phase measurements each time the memory is read. The delay is effective for minimizing visible artifacts which otherwise may tend to occur when displaying "non-standard" video signals wherein the ratio of the color- subcarrier frequency to the line-frequency of the incoming video signal differs from a given broadcasting standard.