I don't think events like the Oscars would be subject to the same type of restrictions on betting as the sports are, which, on top of the common laws, have to comply with the rules of their respective federations/associations etc

Betting on an event that you're directly involved in probably goes against most of the betting sites' terms and conditions, and could expose you to fraud allegations if you're cheating, but I don't think that would be regulated in any special way.