Since Flash is losing ground I would like to know if there are ways to protect html5 videos with DRM (H264, .ogg and WebM).
Probably not, even though there's an EME DRM plug-in interface.
Some browsers now support another type of a plug-in called EME (Encrypted Media Extension CDM) for vendor-specific DRM implementations such as Microsoft PlayReady, Google WideVine, Apple FairPlay, etc.
However, the only part of it that is a public standard is a JS API that launches a vendor-specific EME plug-in.
The actual DRM API required to make use of it is vendor-specific, secret and proprietary. To have working DRM across browsers you will have to sign separate contracts with Adobe, Microsoft, Google and Apple (which may be difficult if you're not Netflix).
Consider abandoning idea of DRM, as it's more likely to backfire than protect the content.
This is an updated answer, comments don't make sense any more