I got my invitation email to the preview of Power BI for Office 365 few days ago and while the provisioning process was pretty straight forward, I run into a minor issue that needed few extra steps that were not covered in the Power BI Provisioning Video. In my case, I did not have Power BI as one of the available apps of the team site I wanted to use as shown in the video (~3:45 in video). Fortunately, there is a provisioning guide document that provide the steps to manually install Power BI app from the SharePoint store.
Thanks to Gilad Elyashar for pointing me in the right direction to get this issue solved by replying to my post in the power BI forum. If you run into this or any other issue, I encourage you to make use of the Power BI forums to get answer to your questions