First and foremost as footer of our web site says: "AmiBroker.com is a software development company and does not provide any kind of investment or brokerage services in financial markets. "
So if you are looking for brokerage “demo” account you should look for brokerages (like Interactive Brokers). IB for example includes Paper Trading account when you can practice your skills.
As for demoing AmiBroker software - it does not require any “account” to use free trial. Just download it from http://www.amibroker.com/download.html
As for real-time stream - you have to choose one of supported data sources http://www.amibroker.com/guide/h_quotes.html
For testing strategy you don’t really need real time stream. You can test strategy using backtester. It is orders of magnitude faster than waiting for real data.
You can also use bar replay feature if you trade from charts. It also allows to practice your skills faster than with streaming data and you are not limited to trading sessions. http://www.amibroker.com/guide/w_barreplay.html