Hi c4cyro,
Sorry you have had this problem for so long. I have not had too much experience fixing PC's with Bluetooth functionality (sadly I don't own one that has one either), but you might to look into the following based on what I observed from your youtube video.
0. Just in case, you may want to see who the manufacturer of your Bluetooth card is, they may be able to provide the best answer, driver, and software support to your problem.
1. Check you computer's device manager by typing device manager in the start menu search and see if any of your devices have a yellow warning icon. If so, you should see what your devices says. You may want to try and disable and then re-enable your Bluetooth function on your PC.
2. Make sure your Wifi / Bluetooth switch is set to on (I know, a simple answer but if you already have another network card installed it could fix your problem).
3. Can your phone or other Bluetooth device detect the PC as a Bluetooth access point (if possible)? If not, then try to reconfigure the device according to
4. Were you at any point since you had your computer able to connect any bluetooth devices, if so, do you remember anything you or someone else may have done while on your PC that may have caused a problem (software, virus / malware, hardware related)?
5. You may need to reinstall your Bluetooth driver or maybe even do a full format, then install your OS and drivers from scratch based on similar complaints I have found while searching for Dell Bluetooth connection problems. Before doing this step though always make sure to make a copy of all the data you find most important...I use Acronis to make a complete image of my computers before doing any intensive troubleshooting / reinstallations. In case I can't fix the issue I restore my data using Acronis and go back to the drawing board.
6. I was thinking that if you do go down the full format and reinstallation of Windows 7, can you check the Device Manager as soon as you complete the process? If the Bluetooth icon shows on your PC and is running, you may want to let Windows take care of your Bluetooth services entirely and forget about Dell's supplied driver. It is possible that computer manufacturers and the companies that manufacturers that make these components make faulty drivers, software.
7. If nothing else here helps...it may be possible that you have a faulty component. A common problem in Dells (I would know by firsthand experience unfortunately).
Please post back if you still have problems or if anything here has helped you so that it helps the community.
Best Wishes
D. Wyatt211