Release 6.50

We've released service release version 6.50. Several improvements were made and new features were added:
- When using header bidding, it's now possible to directly use the ad that belongs to the winning bid.
- Don't want to be delayed by the internet loading elements in your interactive video only on the time they have to appear? Then have our interactivity engine preload them for you.

An overview of bugs that were fixed:
- Enabled big play button for audio players again
- Fixed a bug where playout preview could not always load the ovp demo video clip
- Fixed a bug with the image resizer that caused thumbnails from shared clips to not always be available in the target publication
- Fixed OVP help text 'Use deep link for social links'
- Fixed Player Preroll ads failing to start