Assuming TLS is still unbroken, RTMPS (Flash RTMP over TLS tunnel) offers the most accessible form of end-to-end encryption. To avoid intermediaries you'd have

Assuming TLS is still unbroken, RTMPS (Flash RTMP over TLS tunnel) offers the most accessible form of end-to-end encryption. To avoid intermediaries you'd have to run your own Flash server (e.g. Red5) though.