Having some problems with creating regular expression with subpatterns on php. Need some help.

I have such html code:

```
<div class="result-item *sr "> 
 <a href="/watch?v=_CvG8Eu0nSY" class="ux-thumb-wrap result-item-thumb"><span class="video-thumb ux-thumb-128 "><span class="clip"><img onload="tn_load(1)" alt="Thumbnail" src="//i4.ytimg.com/vi/_CvG8Eu0nSY/default.jpg" ></span></a></div>

```

So I want to have in $matches[0] - "/watch?v=\_CvG8Eu0nSY" and in $matches[1] - "i4.ytimg.com/vi/\_CvG8Eu0nSY/default.jpg".

Thanks for your answers!