how to write an html5 code to upload a video with restricted size?

I've got this small code for uploading files , how can i show the upload button and how can i restrict the up-loader to upload only VIDEOS with specific size?

<input type="file" multiple="true" dojoType="dojox.form.Uploader" label="Select Some Files" url="/tests/UploadFile.php" uploadOnSelect="true"/>