如果有数据拇指，simple_html_dom将不会抓取图像src

I have a problem that i don't understand why it's happening. On some elements where i have data-thumb inside img it won't grab the image src element and i can't figure out why.

Here is an example how html page is formatted. Let's call it somepage.com/search?q=singing

<div class="videos">
    <div class="thumbWrapper">
        <div class="postThumbnail">
           <img id="2019485" class="videoThumb" width="190" height="143" alt="some post title" src="http://imageurl.com/uploaded/image/3.jpg" category="7">
        </div>
    </div>
    <div class="thumbWrapper">
        <div class="postThumbnail">
           <img id="2019485" class="videoThumb" width="190" height="143" alt="some post title" data-thumb="http://imageurl.com/uploaded/image/3.jpg" src="http://imageurl.com/uploaded/image/3.jpg" category="7">
        </div>
    </div>
    <div class="thumbWrapper">
        <div class="postThumbnail">
           <img id="2019485" class="videoThumb" width="190" height="143" alt="some post title" data-thumb="http://imageurl.com/uploaded/image/3.jpg" src="http://imageurl.com/uploaded/image/3.jpg" category="7">
        </div>
    </div>
    <div class="thumbWrapper">
        <div class="postThumbnail">
           <img id="2019485" class="videoThumb" width="190" height="143" alt="some post title" src="http://imageurl.com/uploaded/image/3.jpg" category="7">
        </div>
    </div>
</div>

You see that there is data-thumb on some images, this is totally random, some have that, some not, on a same page.

Here is how i grab a page

            $get = curl_init();
            curl_setopt($get, CURLOPT_USERAGENT,'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13');
            curl_setopt($get, CURLOPT_URL, 'somepage.com/search?q=singing');
            curl_setopt($get, CURLOPT_RETURNTRANSFER, 1);
            curl_setopt($get, CURLOPT_CONNECTTIMEOUT, 10);
            $str = curl_exec($get);
            curl_close($get);

            $URL = str_get_html($str);

And this works or at least i see it works, next step is to extract elements from page and get those thumbs.

            foreach($URL->find('div[class="thumbWrapper"]') as $video) {
                $thumb = $video->find('img[class="videoThumb"]');
                $image = $thumb[0]->src;
                }

And there i get the problem, on img elements where i have

data-thumb

It won't get an image.

On the simplehtmldom page it just says that i need to use like

$video->find('img');
$thumb->src;

But it won't work, i had to specify img class and use a [0] of an array. But i guess when there is data-thumb array is shifted so src is not more [0] in an array?

I don't know i just started using simplehtmldom and still learning, any suggestions?

I have found kinda workaround with this

                if($thumb[0]->{'data-thumb'} != '') {
                    $image = $thumb[0]->{'data-thumb'};
                } else {
                    $image = $thumb[0]->src;
                }

I don't know if it's best approach, but it works, if data-thumb exist get that image, else get src.