VLC seems to be corrupting files.

[Ugg Smash]

I used VLC for years, amazing program. A few days ago, I downloaded some .mp4 files off youtube using DownloadHelper. I've done this for the last year, never an issue.
I was watching each file and renaming it, and then when I went to play one again, VLC opened, but nothing happened. I tried again, nothing. I tried another file, nothing.
I restarted the pc, and tried the same two files, nothing. No crash, VLC was still open, but just nothing happened. I tried openning the files from inside VLC, nothing, no error msg or crash.
So I started trying other files. Some worked, all of the same type/source. Then I tried openning other movie files. Some worked, others didn't.

I copied them onto a usb and played them on the tv. The files no longer worked on the tv either, it said "Invalid codecs". These are movies I've watched on the tv before, so somehow the files got corrupted.
The day all this started, I only did one thing differently, and that is install the lasted patch for the Hanger Module for the upcoming game Star Citizen. I searched their forums, and some people had issues with VLC crashing if it was open when they started the Hanger module, but not the same as mine.

So now I'm too scared to open any other movie files as it has a random chance to corrupt the file permanently. Its not every file either. I thought maybe its a certain type of codecs, but my computer knowledge is very limited. A guy on the Star Citizen forums suggested using a little program to see what codecs the files were using. But the corrupted files(if thats the right term to use), no longer had any codecs or information, like all file information had been wiped, which would be why VLC can't play it anymore.

I copied working files to usb and tested on tv. Worked. Played all on the pc, some worked, others were corrupted again, and then wouldn't work on the tv as in previous trial and error runs.
I've run AVG, no viruses turned up, and now have come to the limit of my very limited computer knowledge.

Any help would be appreciated,
Ugg

[Ugg Smash]

Running Windows 7, 64 bit
AMD FX 8350 Eight Core 4.33GHz
16mg RAM
AMD Radeon HD 7800 series (7890 i think)

Not sure what other info to give.

[kodela]

What version of VLC are you using?

[Ugg Smash]

2.1.2

When it first started a couple days ago, I had an earlier version. I uninstalled VLC, and install the latest version there was. Problem was still there, so figured it was a version issue. Sorry, forgot to mention that.

[Jean-Baptiste Kempf]

Youtube changed their schema, so most new downloads are corrupted.

VLC does not modify random files.

[Ugg Smash]

That explains the youtube side, but not why random movie/tv files are now stuffed. I'm not convinced its VLC, but every of file type is fine. If I redownload the file and play it in Media Player it works.
I'll keep testing, thanks for the response.