Joseph Chirilov has written a series of 3 posts showing exactly how to build a fully functioning media player inside Excel.
While we are talking about Joseph's site I want to highlight two other posts that are there.
The following is a list of applications I installed on Vista business 64 bit in the last 2 days (my must install list). These were all successful (after in some cases downloading the latest version).
The following software would not install or doesn't work properly on Vista 64 bit.
Microsoft has recently introduced a free Word 2007 viewer that lets you view docx Word documents, even if you don't have any version of Word installed. This does away with the need to download the Office 12 Compatibility Pack or manually convert .docx to .doc format using any of the online conversion services to open a Word 2007 document. To use the viewer you will still need to install the Office Compatibility Pack.
Microsoft has also provided a Powerpoint 2007 viewer for pptx presentations. There is currently no Excel 2007 viewer however you can convert xlsx to xls using Zamzar and then view the converted spreadsheet in Google Docs.