Is it possible to change the long name of : "Archivo de la Categoria: Formación" (just as an example) and simply say: "Archivo: Formación" or "Formación".

It's actually quite tricky, but something like this might work:

.archive .page-header {
	overflow: hidden;
}

.archive .page-title {
	visibility: hidden;
	float: left;
	margin-top: -1.3em;
}

.archive .page-title span {
	visibility: visible;
	float: left;
}

.archive .page-title span:before {
	content: "Archivo: ";
}

it´s visible thanks to your incredible help - the name of "blogroll" that appears on the left column (secondary column). I want to change its name to: "webs recomendadas" How can i do it?

Go to Appearance → Links, click on any link and add a category named "webs recomendadas," uncheck the "Blogroll" category and save changes. Then edit each link and update each one to use the new category you created.

http://agendacix.com/category/formacion/

If you wait at least an hour and then check again, do the thumbnails look correct after that?

If you're still having trouble, could you please point out a very specific example (i.e. a link to a post where the video thumbnail hasn't updated yet) and describe exactly what the updated thumbnail is supposed to look?

#colophon {
	color: #9c6409;
}
#colophon a {
	color: #bd790a;
}

.widgettitle {
	color: #000;
}

And I want also want to change the color of the headers or titles of the pages because they are also grey to a red color #B40404.

Here is an example that will change the color of titles on pages as well as the not found page:

body.page .type-page .entry-title,
.not-found .entry-title,
.page-title {
	color: #B40404;
}

I found this by using a web inspector—which most modern browsers have built in. To use it, right-click on an element such as the page title and select the "Inspect Element" option. It should pull up the HTML as well as the CSS that applies to it on the right. You should be able to see what selector list the theme is using and copy that to set a new color.

Also, here is a link to some CSS basics in case you're interested:
http://www.htmldog.com/guides/cssbeginner/

I want to change the color of the link "Comments" of each post because they are grey and arent visible. I want them in blue #0B0B61.

I can give you some CSS to help you get started.

This will change all of the links below the post title to blue but keep the category links that appear at the top right of featured images on the home page gray:

.entry-meta,
.entry-meta a,
.entry-meta .entry-format,
.single .entry-meta a,
body.page .type-page .entry-meta a  {
	color: #0B0B61;
}
.cat-links a {
	color: #bbb;
}

You may also want to set the link color for the current menu item to a dark color:

.main-navigation li.current_page_item a,
.main-navigation li.current-menu-item a {
	color: #0B0B61;
}

At this time, we don't have a way around that requirement.

wordpress.com
<yourblog>.wordpress.com
public-api.wordpress.com

First, please make sure that your browser is up to date by visiting http://whatbrowser.org/

If it is not, please try updating your browser or switching to a different browser.

If it is, please do these four things:

1. Try clearing your browser's cache and cookies: http://en.support.wordpress.com/browser-issues/

2. Make sure that you have third-party cookies enabled: http://en.support.wordpress.com/third-party-cookies/

3. Try with all browser extensions or add-ons temporarily disabled.

4. Try enabling HTTPS: http://en.support.wordpress.com/https/

Please let us know how each step goes for you, and which browser (and version of) you're using if you're still having trouble.

any plans to fix this? at the moment there is absolutely no way for me to upload videos through my selfhosted blog. but i have to login to the wordpress.com blog, do everything there and then copy the embed-code over. that used to be A LOT more convenient...

what is the reason behind that sameorigin header? this makes the whole popup in the videopress plugin unusable. at the moment it seems as if the popup shows me the login-page again, but i cannot login anymore. any reason why videopress integration for selfhosted pages is so broken at the moment? it used to work fine a month ago...

You can still upload via Media -> Add New in your WordPress.com blog's Dashboard and obtain the embed code from there.

Is there any improvement with the embedded video with Jetpack?