OFDM modulation, which has been adopted for the digital video broadcasting (DVB-T) standard in Europe, has been recognized for its good performance for high data rate wireless communications. Therefore, the study of the robust transmission of multimedia data over OFDM systems has attracted extensive research interest. In the past, channel estimation, which is an important aspect in OFDM systems, has not been exploited for multimedia transmission. When using block-training based channel estimation schemes, there exists a periodic variation of the error rates due to channel estimation imprecision. We use this property to provide unequal error protection (UEP) for video transmission. Compared with systems using pilot-training based channel estimation schemes, which are recommended in the DVB-T standard, a performance gain of about 2dB in the PSNR of the reconstructed images is achieved.