Looks like the Warner Archive Collection has a streaming service in Beta: http://criterioncast.com/news/warner-archive-collection-launches-streaming-service/
I've been sampling a few things the last few days. HD content is hit or miss. The Loved One listed as HD doesn't look like it to me. Amercanization of Emily posted as HD looks very good. Doc Savage not HD looks decent enough while Until the End of the World is window boxed and looks awful