This is very interesting overview of how much powerful HTML 5 is going to be.
Google, Mozilla, Opera and Safari are working together to bring more power to the web.
Here is an over view of video, but i will highly recommend that you should watch the full video.
In HMTL 5 how easy it will be to control the graphics of browser simply with Java script.
There will be Full 3D objects support.
In HTML 5 there is a new tag called video in order to simply play a video. You just need to specify the URL of video browser takes care of the rest. Plus many more features.
In HTML 5 browsers will be able to track you location not only by IP. But also using Wifi connection or Cell phone ID & mobile network .
3) Offline Availability of Web Data (App Cache Database)
HTML 5 has built in support of application cache in case you are disconnected or go offline you will be still able to interact with you apps.
Most powerful thing in HTML 5 is that you can create background process, so that user experience is smooth.
5)Google Web Tool Kit
Google web tool kit is easy way to go ahead with HTML 5 as along with other more features it automatically take care of web browser and render the Java Script accordingly.
6)Google Web Elements
I think its very good idea that applying AddSens, Youtube Video Embed technique to all other services of googles like google news etc.