Hey Amit,
Great questions! Thanks for posting that link as well - love seeing stats on video!
I work at Vidyard, and we use video in just about all of our campaigns - from landing pages to emails. Here's my learning lessons:
Length
We've found that length varies depending on your audience, but under 2 minutes is pretty key for most content. Our home page video is 1:30, and our explainer content for integrations and features all clocks in under 2 minutes. For prospects that are in the later stages of your sales funnel, longer content may still be engaging - especially if the prospect is ready to buy. But keep in mind, even a 30 minute recorded webinar can be daunting. Breaking up longer videos into smaller chapters lets viewers engage with as much of the video as they want, and still lets you track engagement by seeing who watched everything from start to finish.
Quality
Blake Smith is our creative director, and handles most of our video content in-house. That being said, a high-quality camera with an on-staff videographer isn't a requirement. The Kickstarter video for the Pebble watch was filmed with an iPhone, and is an awesome example of do-it-yourself video for a wildly successful crowd funding campaign:
Pebble Kickstarter Video from Pebble Technology on Vimeo.
Video Players
We're a bit biased on this front. We use Vidyard, but we also push a large portion of our content on YouTube in addition to hosting it ourselves for our players. It is the second largest search engine out there, so it's worth paying attention to.
Also take care to pick your splash screen - it's the image people see before they click play, and a compelling splash screen is a must if you want to encourage people to watch.
Gating
Video plays a key role in Vidyard campaigns - we share links to it via our emails, and video is on just about every page on our site. Some content is gated, like our integration videos and content we use as part of our lead generation strategy. Our Video Thought Leadership series, and our Vidyard How-To videos are all ungated, as we want anyone to be able to watch them with as little friction as possible.
Those are a few of the things I've learned since I started working with video. Ian Hutchinson may have some knowledge to add as well.
Would love to hear how others are using video - we're learning a lot ourselves as we develop our content, and find new ways to share it!