$re = '/gamers_online.*\s*(\d+),?(\d+),?(\d+)/';
$str = '[...]
<div id="about_header_area" class=" global">
<div class="about_area_inner_wrapper">
<div id="about_monitor_video">
<video width="100%" height="auto" autoplay muted loop playsinline poster="https://cdn.fastly.steamstatic.com/store/about/videos/about_hero_loop_web.png">
<source src="https://cdn.fastly.steamstatic.com/store/about/videos/about_hero_loop_web.webm" type="video/webm">
<source src="https://cdn.fastly.steamstatic.com/store/about/videos/about_hero_loop_web.mp4" type="video/mp4">
</video>
<div id="about_monitor_video_gradient"></div>
</div>
<div id="about_header">
<div id="about_greeting">
<div class="about_greeting_header">
<div class="steam_logo"><img src="https://cdn.fastly.steamstatic.com/store//about/logo_steam.svg" alt="The logo for Steam"></div>
<div class="about_subtitle">Steam is the ultimate destination for playing, discussing, and creating games.</div>
<div class="online_stats">
<div class="online_stat">
<div class="online_stat_label gamers_online">online</div>
36,426,658 </div>
<div class="online_stat">
<div class="online_stat_label gamers_in_game">playing now</div>
10,289,777 </div>
</div>
</div>
<div class="about_install_wrapper">
<div class="about_install win ">
<a href="https://cdn.fastly.steamstatic.com/client/installer/SteamSetup.exe" class="about_install_steam_link">Install Steam</a>
</div>
<div class="installer_list">
<div class="available_platforms">
Also available on:
</div>
<a class="platform_icon" href="https://cdn.fastly.steamstatic.com/client/installer/steam.dmg">
<img src="https://cdn.fastly.steamstatic.com/store/about/icon-macos.svg">
</a>
<a class="platform_icon" href="https://cdn.fastly.steamstatic.com/client/installer/steam.deb">
<img src="https://cdn.fastly.steamstatic.com/store/about/icon-steamos.svg">
</a>
<a class="platform_icon" href="https://support.google.com/chromebook?p=steam_on_chromebook">
<img src="https://cdn.fastly.steamstatic.com/store/about/icon-chromeos.svg">
</a>
</div>
</div>
</div>
</div>
</div>
<div class="learn_more_btn">
<a href="#about_games_cta_area" class="smooth_scroll">
Learn more <span class="down_arrow"></span>
</a>
</div>
</div>
';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php