No. DaCast uses a version of OpenSSL to generate certificates that was not impacted.
Heartbleed, a major vulnerability discovered in OpenSSL on April of 2014, only affects OpenSSL's 1.0.1 and the 1.0.2-beta release. On the internet as a whole, 1.01 is already broadly deployed on many websites including Facebook and Google. Since Secure-Socket Layer (SSL) and Transport Layer Security (TLS) are at the heart of Internet security, this security hole is serious.
DaCast uses a different version of OpenSSL, version 0.9.8k that was released on the 25th of March, 2009. This version is not the one that was compromised by Heartbleed and DaCast broadcasters and viewers have no need to change their password in response to Heartbleed.