In December 2013 the 9th Circuit livestreamed the oral arguments in five en banc cases. It is likely the court will schedule additional livestreaming in the future; visit the court's website www.ca9.uscourts.gov for current livestreaming information.
Digital files containing recordings of court proceedings, almost all audio-only, are available online at http://www.ca9.uscourts.gov/media/. This database of cases goes back as far as 2004. The court now uploads audio recordings by noon the day after oral arguments.
Keep in mind that the courthouse is just a few blocks from UC Hastings, so you can attend these hearings live -- but if your schedule doesn't allow that, there is likely to be a recording available.