I can't seem to drag and drop more than one video on my timeline ? Only the audio will appear ?

Question

Hello, I've been working on Premiere for a year now
I installed 2014 a week ago, and until today I haven't had any problems.
When I drag and drop the first video, everything works fine, until I try to drop another video.
The second video won't appear on the timeline, except for it's audio
Which is weird to me because everything worked well on the CS6
My sequence settings are
Custom
30 frames/second
16/9
sample rate : 44100Hz
quickTime
+H.264
The first video's properties:
Type: MPEG Movie
File Size: 576,0 MB
Image Size: 1920 x 1080
Frame Rate: 30,00
Source Audio Format: 44100 Hz - compressed - Mono
Project Audio Format: 44100 Hz - 32 bit floating point - Mono
Total Duration: 00:04:41:28
Pixel Aspect Ratio: 1,0
The second video's properties:
Type: MPEG Movie
File Size: 583,1 MB
Image Size: 1920 x 1080
Frame Rate: 29,97
Source Audio Format: 48000 Hz - compressed - Stereo
Project Audio Format: 48000 Hz - 32 bit floating point - Stereo
Total Duration: 00:04:45:15
Pixel Aspect Ratio: 1,0
(it's a .MTS)
What is weird, too, is that when I added the first video, I couldn't add it "Again", the same thing happened
Any help? I need to finish the project by tonight :/

Answer 1

My QuickTime version is the 10.4 (no idea if it's the latest one)
What do you mean by my system properties ? My mac ? If so then its a 16Gb 1600MHz DDR3 + Nvidia Geforce GT 750M 1024MB, an OS X Yosemite version 10.10
"What happens when you import the files onto a non-quicktime sequence?", well I don't know how to create a sequence before dragging a file on the timeline on this premiere, so I dragged the "Second video" first and it created a sequence with AVC Intra 100 1080i
29,97 frames/second
preview file format AVC-intra class100 1080i
what's weird is that I could add the second video once, but not twice, and I can add the "first" video several times (it's weird because the sequence was created from the second video's properties)
To answer your last question, the same thing happens too. I can create another sequence with the "Second video", add the "First video" 10 times but I won't be able to add the second video a second time.
On the other hand, when i created another sequence with the "first video", I will be able to add the first video as much as I want, but I won't even be able to add the "second" video once.