While playing around for a project, i found a way to embed a slideshow and then thought to build an app around. Don’t know if i should ask for a specific new card type or confirmation to use as player.
I’ve read the do’s & dont’s and try to explain, why i’m concerned or cannot meet the rules, hoping for a ‘fair-use’-allowance 
In the prototype state now, i would like to embed instagram pics & videos, uncached webcam images/videos, slider of square pics (extracted from a CMS), but could build a realtime webapp around, for companies to use (like Google AMP or Facebook Instant Articles).
Do:
Test your experience across all Twitter clients, including Twitter’s iPhone and Android apps, as well as twitter.com and mobile.twitter.com.
-> It’s a different, but seamless user-experience for mobiles and on desktop. Depends on device which ‘canvas’ and body would happen. mobile will jump to mobile (landing) website, desktop and mobile.twitter.com is displayed inline, autoplay slider.
Do not:
Respect user privacy -> right now (prototype) is enabled, but for a product i would like to have the possibility to get the users twitter email (sign on twitter on iframe)
All with respect and to be a good partner to Twitter
Do not circumvent the intended use of the Card. Player Cards are reserved for linear audio and video consumption only. -> thats why i wanted to ask for ‘fair-use’ allowance or a new twittercard
Do not require users to sign-in to your experience. -> they dont need to login for the card content, but its possible on the landingpage (twitter:player), out of the iFrame.
Do not attach additional interactivity outside the video or audio player (e.g., banners or non-standard buttons).
-> would display the slider fullscreen 480x480
Do not build end-to-end interactive experiences inside the video or audio player unrelated to Player Card content, such as the following: purchasing, gaming, polling, messaging, and data entry. Instead, build these interactive experiences with our other Card types or enhance your Player Card content with links to your website or mobile application. -> for an extended card, i would like to have kind of ‘micropayment’ enabled. Specific metatags scraped from URL.