In the field of video protection, selective encryption (SE) is a scheme which ensures the visual security of a video by encrypting only a small part of the data. This paper presents a new SE algorithm for H.264/AVC videos in CAVLC mode. This algorithm controls the amount of encrypted alternative coefficients (AC) of the integer transform in the entropic encoder. Two visual quality measures, the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM), are used to measure the visual confidentiality level of each video frame and to control the amount of encrypted AC. Moreover, a new psychovisual metric to measure the flickering is introduced, the so-called TSSIM. This method can be applied on intra and inter frame video sequences. Several experimental results show the efficiency of the proposed method.