I had the Dell 1558 too! And had the exact video problem happen with any and every video player I would use.
So, most likely it's hot because of dust.
So firstly, get a can of compressed air and blow out all the dust from every fan inlet/outlet.
I actually recently disassembled my laptop and used the compressed air again but inside, and TONS of dust came out. So even using the compressed air without opening it up may not be enough. BTW I'm not super tech savvy so believe me when I say it's not as hard as you think to open up and close up the laptop. (This is just an option but this is the video I used to open it up
http://youtu.be/p6SrUkNVqTs)
Secondly, for the video crashes, back up everything and reinstall the OS like WyomingKnott said. I know it's a hassle but you get a cool new experience and will probably never go back to using stock OS's due to the bloatware.
Replacing the operating system is the BEST option. One option worth trying before reinstalling the OS is to download the graphics driver from the Dell Drivers Website but don't install it. Run Display Driver Uninstaller (
http://www.guru3d.com/files-details/display-driver-unin...) and that will completely delete any remnants of your display driver and it will revert back tot he Standard VGA driver. Now install the Dell Display Driver, then update it to the most up to date driver from the AMD website (if you have one of the 2 ATI video cards, ignore if you don't)
Thirdly, I am saying this part because I had the exact same problem as you right before my graphics card overheated and permanently damaged it. Do the above 2 things ASAP and blow out the air regularly (every 2 months-ish even more often). If you can, open up the laptop once and blow the air everywhere to get as much dust out as possible (I even took out the whole mother board [don't remove the CPU/GPU tho]). Warning: opening it up may void your warranty if you still have it.
The Dell GPU (graphics card) is integrated into the motherboard. So if it gets damaged then you have to get a whole new motherboard and if you don't have your warranty it's gonna be expensive.