The increased popularity of multimedia applications places a great demand on the security of multimedia content during transmission. Many digital applications such as Internet telephony, internet conferencing, internet security monitoring, video conferencing, pay-per-view, video-on-demand, medical image transmission, interactive video games require reliable security and confidentiality. As the full encryption conventional approaches provide very high security rather than partial/selective or transparent encryptions, the encryption of block ciphers in video streaming is analyzed. The sender encrypts the entire data stream and the immediate playback while decryption can be performed simultaneously at the receiver end is analyzed using AES, RC6 and IDEA. Thus a client player can begin playing the data in real time before the entire file has been decrypted. The performance of block ciphers AES, RC6 and IDEA are measured in terms of encryption time, speed and the startup latency. Experimental results showed the efficiency of block encryption in real-time and is able to manage the tradeoffs between the security and speed, and hence suitable for real-time secure video communication applications.